[clang-tidy] Add clang-tidy headers to clang distribution

Summary:
Clang releases include static libraries for clang-tidy but corresponding
headers are missing in the tarball so these libraries are almost useless.
Clang-tidy libraries can be useful for build custom clang-tidy with
custom checks outside of llvm repo.

List of clang-tidy libraries included in clang 9.0.1 release:
    lib/libclangTidyMPIModule.a
    lib/libclangTidyPlugin.a
    lib/libclangTidyBoostModule.a
    lib/libclangTidyCERTModule.a
    lib/libclangTidyAndroidModule.a
    lib/libclangTidyPortabilityModule.a
    lib/libclangTidyPerformanceModule.a
    lib/libclangTidyOpenMPModule.a
    lib/libclangTidyBugproneModule.a
    lib/libclangTidyZirconModule.a
    lib/libclangTidyCppCoreGuidelinesModule.a
    lib/libclangTidyGoogleModule.a
    lib/libclangTidyUtils.a
    lib/libclangTidyHICPPModule.a
    lib/libclangTidyModernizeModule.a
    lib/libclangTidyLLVMModule.a
    lib/libclangTidyAbseilModule.a
    lib/libclangTidyReadabilityModule.a
    lib/libclangTidyFuchsiaModule.a
    lib/libclangTidyMiscModule.a
    lib/libclangTidy.a
    lib/libclangTidyObjCModule.a

Reviewers: smeenai, jdoerfert, alexfh, hokein, aaron.ballman

Subscribers: mgehre, mgorny, xazax.hun, cfe-commits

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D73236