Update clang tidy Contributing guide (#106672)

Update the documentation to direct new users to the Github instead of
the discontinued Phabricator archive. Also details more ways and
information regarding clang-query usage. Partially resolves/disclaims
#106656 and #106663 as per discussion in
https://discourse.llvm.org/t/inconsistency-between-hasdescendant-in-clang-query-and-clang-libtooling-matchers/80799/.

Also updates the out-of-tree guide.

For context, I recently went through the Contributing guide while
writing https://github.com/llvm/llvm-project/pull/102299, and many of
these updates were from my experience trying to follow the guide. e.g. I
was trying to link the shared library of an out-of-tree check as SHARED
in CMake and encountered duplicate symbols like
_ZTIN5clang4tidy14ClangTidyCheckE. It wasn't until I saw
https://github.com/llvm/llvm-project/commit/84f137a590e7de25c4105303e5938c40566c2dfb
that I found out I had to use MODULE. I also encountered the clang-query
difference which was a surprise as the documentation said the two
matchers were "virtually identical". Also, the -header-filter thing
tripped me out until I found
https://github.com/llvm/llvm-project/issues/25590 and
https://github.com/llvm/llvm-project/pull/91400. Usually, when people
say restrict and filter, they mean filter out (since -header-filter
instead includes/filters in said headers).

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