[clang-tidy] Use new ASTMatchers to identify template instantiations instead of copying it everywhere.

No intended functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@217035 91177308-0d34-0410-b5e6-96231b3b80d8
[clang-tidy] Eliminate inline copies of InTemplateInstantiation matcher.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@217036 91177308-0d34-0410-b5e6-96231b3b80d8