Don't require erc-goodies in erc.el

Don't require erc-goodies in erc.el

* lisp/erc/erc-goodies.el: Obviate the need for forward declarations
by requiring `erc'.  Add minor-mode autoloads for `scrolltobottom',
`readonly', `move-to-prompt', `keep-place', `noncommands',
`irccontrols', `smiley', and `unmorse'.  Add Local variables footer
with `generated-autoload-file'.
(erc-controls-strip): Autoload this function.
* lisp/erc/erc-ibuffer.el: Require `erc-goodies' for
`erc-control-interpret'.  The justification for the blanket `require'
is this module isn't a member of `erc-modules' by default.
* lisp/erc/erc-page.el: (erc-ctcp-query-PAGE): Require `erc-goodies'
and put forward declaration for `erc-control-interpret' atop file.
* lisp/erc/erc-speedbar.el: Require `erc-goodies' for the same reason
as erc-ibuffer.el.
* lisp/erc/erc.el: Remove `require' for `erc-goodies' at end of file
and `pp' at top of file because `pp-to-string' is autoloaded on Emacs
27.  Also remove `require's for `thingatpt', `time-date', and
`iso8601'.  They're all used sparingly and the latter two have only
been around for one major release, so their removal likely won't cause
much churn.  And `thingatpt' already has a call-site `require', so the
top-level one is redundant, but autoload `word-at-point' anyway for
the benefit of third-party libraries like `hl-nicks'.  Also wrap local
loaddefs `require' call in `eval-and-compile'.
(erc--read-time-period): Require dependencies.  (Bug#60954.)