Add user-oriented test scenarios for ERC

Add user-oriented test scenarios for ERC

* test/lisp/erc/erc-scenarios-base-association-nick.el: New file.
* test/lisp/erc/erc-scenarios-base-association-samenet.el: New file.
* test/lisp/erc/erc-scenarios-base-association.el: New file.
* test/lisp/erc/erc-scenarios-base-compat-rename-bouncer.el: New file.
* test/lisp/erc/erc-scenarios-base-misc-regressions.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-bouncer-id.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-bouncer-recon-base.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-bouncer-recon-both.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-bouncer-recon-id.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-bouncer.el: New file.
* test/lisp/erc/erc-scenarios-base-netid-samenet.el: New file.
* test/lisp/erc/erc-scenarios-base-reconnect.el: New file.
* test/lisp/erc/erc-scenarios-base-renick.el: New file.
* test/lisp/erc/erc-scenarios-base-reuse-buffers.el: New file.
* test/lisp/erc/erc-scenarios-base-unstable.el: New file.
* test/lisp/erc/erc-scenarios-base-upstream-recon-soju.el: New file.
* test/lisp/erc/erc-scenarios-base-upstream-recon-znc.el: New file.
* test/lisp/erc/erc-scenarios-misc.el: New file.
* test/lisp/erc/erc-scenarios-services-misc.el: New file.
* test/lisp/erc/resources/base/assoc/bouncer-history/barnet.eld: New file.
* test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld: New file.
* test/lisp/erc/resources/base/assoc/bumped/again.eld: New file.
* test/lisp/erc/resources/base/assoc/bumped/foisted.eld: New file.
* test/lisp/erc/resources/base/assoc/bumped/refoisted.eld: New file.
* test/lisp/erc/resources/base/assoc/bumped/renicked.eld: New file.
* test/lisp/erc/resources/base/assoc/multi-net/barnet.eld: New file.
* test/lisp/erc/resources/base/assoc/multi-net/foonet.eld: New file.
* test/lisp/erc/resources/base/assoc/reconplay/again.eld: New file.
* test/lisp/erc/resources/base/assoc/reconplay/foonet.eld: New file.
* test/lisp/erc/resources/base/assoc/samenet/chester.eld: New file.
* test/lisp/erc/resources/base/assoc/samenet/tester.eld: New file.
* test/lisp/erc/resources/base/assoc/samenet/tester2.eld: New file.
* test/lisp/erc/resources/base/channel-buffer-revival/foonet.eld: New file.
* test/lisp/erc/resources/base/flood/soju.eld: New file.
* test/lisp/erc/resources/base/gapless-connect/barnet.eld: New file.
* test/lisp/erc/resources/base/gapless-connect/foonet.eld: New file.
* test/lisp/erc/resources/base/gapless-connect/pass-stub.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/barnet-again.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/barnet-drop.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/barnet.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/foonet-again.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/foonet-drop.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/foonet.eld: New file.
* test/lisp/erc/resources/base/netid/bouncer/stub-again.eld: New file.
* test/lisp/erc/resources/base/netid/samenet/chester.eld: New file.
* test/lisp/erc/resources/base/netid/samenet/tester.eld: New file.
* test/lisp/erc/resources/base/reconnect/aborted-dupe.eld: New file.
* test/lisp/erc/resources/base/reconnect/aborted.eld: New file.
* test/lisp/erc/resources/base/reconnect/options-again.eld: New file.
* test/lisp/erc/resources/base/reconnect/options.eld: New file.
* test/lisp/erc/resources/base/reconnect/timer-last.eld: New file.
* test/lisp/erc/resources/base/reconnect/timer.eld: New file.
* test/lisp/erc/resources/base/renick/queries/bouncer-barnet.eld: New file.
* test/lisp/erc/resources/base/renick/queries/bouncer-foonet.eld: New file.
* test/lisp/erc/resources/base/renick/queries/solo.eld: New file.
* test/lisp/erc/resources/base/renick/self/auto.eld: New file.
* test/lisp/erc/resources/base/renick/self/manual.eld: New file.
* test/lisp/erc/resources/base/renick/self/qual-chester.eld: New file.
* test/lisp/erc/resources/base/renick/self/qual-tester.eld: New file.
* test/lisp/erc/resources/base/reuse-buffers/server/barnet.eld: New file.
* test/lisp/erc/resources/base/reuse-buffers/server/foonet.eld: New file.
* test/lisp/erc/resources/base/upstream-reconnect/soju-barnet.eld: New file.
* test/lisp/erc/resources/base/upstream-reconnect/soju-foonet.eld: New file.
* test/lisp/erc/resources/base/upstream-reconnect/znc-barnet.eld: New file.
* test/lisp/erc/resources/base/upstream-reconnect/znc-foonet.eld: New file.
* test/lisp/erc/resources/erc-scenarios-common.el: New file.
* test/lisp/erc/resources/networks/announced-missing/foonet.eld: New file.
* test/lisp/erc/resources/services/password/libera.eld: New file.

Add test cases for locking down fundamental client behavior, much of
it involving the relationship between buffers and connections.  Also
add accompanying resources subdir containing canned dialog scripts and
common code needed by various tests.  For test cases demoing the
problematic behavior originally described in the initial report, see
update #4 on the bug tracker thread for bug#48598.  Most reside in a
file named test/lisp/erc/erc-scenarios-48598.el introduced by the
patch "Add user-oriented test scenarios for ERC".