Skip indentation when gathering faces in erc-track

Skip indentation when gathering faces in erc-track

* lisp/erc/erc-nicks.el (erc-nicks-mode, erc-nicks-enable)
(erc-nicks-disable): Use correct name for `track' module hook.
(erc-nicks--check-normals): Remove falsity from doc string.
* lisp/erc/erc-track.el (erc-make-mode-line-buffer-name): Don't error
when optional COUNT is nil.
(erc-track-modified-channels): Use new name for preferred face-finding
function.
(erc-track--get-faces-in-current-message, erc-track--collect-faces-in):
Rename former to latter to better reflect expanded utility, which now
includes spanning gaps, including newlines and indentation that may be
lacking in face-related properties.
* test/lisp/erc/erc-track-tests.el (erc-track--collect-faces-in): New
test.  (Bug#73443)

(cherry picked from commit df593b5a619d63b620f8fd569ecf032dab2602d9)