More clearly define local module behavior in ERC

More clearly define local module behavior in ERC

* doc/misc/erc.texi (Modules): Label all local modules as being such.
Move `querypoll' to the auxiliary section.  Rework entire "Local
Modules" portion.
* lisp/erc/erc-goodies.el (erc-keep-place-indicator-mode)
(erc-command-indicator-mode): Mention what buffer types they operate in.
* lisp/erc/erc-nicks.el (erc-nicks-mode): Mention the mode is enabled in
all buffers.
* lisp/erc/erc-notify.el (erc-querypoll-mode): Mention which buffers it
operates in.
* lisp/erc/erc-sasl.el (erc-sasl-mode): Disable completely in target
buffers so its mode variable is nil.
* lisp/erc/erc-services.el (erc-services-regain-mode): Disable in target
buffers.
* lisp/erc/erc.el (erc-open): When activating local modules, skip those
that have just been enabled by a fellow module.  Do this even though
their setup code is meant to be idempotent.
* test/lisp/erc/erc-scenarios-base-local-modules.el
(erc-scenarios-base-local-modules--toggle-helpers): Revise to assert
current behavior.  (Bug#57955)

(cherry picked from commit e9408918f4e7fe00eb4e25e1e5428fb26c4ad847)