Move "clang/Basic/TokenKinds.h" into a separate top-level module.

[vsapsai]

Summary

Fixes modular build for clangPseudoGrammar from clang-tools-extra.

Starting from https://reviews.llvm.org/D126731 clangPseudoGrammar
doesn't depend on generated .inc headers but still depends on
"Basic/TokenKinds.h". It means clangPseudoGrammar depends on module
'Clang_Basic' which does depend on generated .inc headers. To avoid
these coarse dependencies and extra build steps, extract
"clang/Basic/TokenKinds.h" into a top-level module 'Clang_Basic_TokenKinds'.

rdar://97387951

[sammccall]

Thank you!

[vsapsai]

Thanks for the reviews!

clang/include/clang/module.modulemap

module Clang_Basic {
   textual header "Basic/OpenCLImageTypes.def"
   textual header "Basic/OpenCLExtensionTypes.def"
   textual header "Basic/OpenMPKinds.def"
   textual header "Basic/OperatorKinds.def"
   textual header "Basic/PPCTypes.def"
   textual header "Basic/RISCVVTypes.def"
   textual header "Basic/Sanitizers.def"
   textual header "Basic/TargetCXXABI.def"
-  textual header "Basic/TokenKinds.def"
 
   module * { export * }
 }
+module Clang_Basic_TokenKinds {
+  requires cplusplus
+
+  header "Basic/TokenKinds.h"
+  textual header "Basic/TokenKinds.def"
+
+  export *
+}
 
 module Clang_CodeGen { requires cplusplus umbrella "CodeGen" module * { export * } }
 module Clang_Config { requires cplusplus umbrella "Config" module * { export * } }
 
 // Files for diagnostic groups are spread all over the include/clang/ tree, but
 // logically form a single module.
 module Clang_Diagnostics {
   requires cplusplus