SC3014: Offer a quickfix, as it is trivial

[stdedos]

For bugs

• Rule Id (if any, e.g. SC1000): SC3014
• My shellcheck version (shellcheck --version or "online"): 0.9.0
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on https://www.shellcheck.net/ and verified that this is still a problem on the latest commit

For new checks and feature suggestions

• https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related https://github.com/koalaman/shellcheck/issues?q=is%3Aissue+SC3014+offer+fix

Here's a snippet or screenshot that shows the problem:

shellcheck/src/ShellCheck/Checks/ShellSupport.hs

Lines 217 to 218 in d1d574c

	bashism (TC_Binary id SingleBracket "==" _ _) =
	warnMsg id 3014 "== in place of = is"

Here's what shellcheck currently says:

In input.sh line 10:
    if [ "$#" == 0 ] ; then
              ^-- SC3014 (warning): In POSIX sh, == in place of = is undefined.

For more information:
  https://www.shellcheck.net/wiki/SC3014 -- In POSIX sh, == in place of = is ...

Here's what I wanted or expected to see:

... "fix" also

shellcheck/src/ShellCheck/Checks/ShellSupport.hs

Lines 217 to 218 in d1d574c

	bashism (TC_Binary id SingleBracket "==" _ _) =
	warnMsg id 3014 "== in place of = is"

 bashism (TC_Binary id SingleBracket "==" _ _) = 
         warnWithFix id 3014 "== in place of = is" (replaceToken id params "==" "=")

... or something equivalent/correct 😅 🥵