[HLSL][RootSignature] Add lexing support for floating points (#137720)

- this takes care to add support to match the [behaviour of
DXC](https://github.com/microsoft/DirectXShaderCompiler/blob/34b6d0f91e6afd523bdc574836093f021713cce7/tools/clang/lib/Parse/HLSLRootSignature.cpp#L74)
acceptable floating point integers

Namely:
- Allow for specifying the decimal '.'
- Allow for specifying exponents with 'e' or 'E' and allow for 'f' to
denote an otherwise interpreted integer as a float

This pr is simply responsible of creating a token that could be
interpeted as a floating point integer by `NumericLiteralParser`. As
such, we are not required to validate that the special characters only
occur once and that 'f' is only at the end of the string. These will be
validated when invoking `NumericLiteralParser` during parsing.

Resolves #126565

GitOrigin-RevId: 8e4dd21e6362ca161b7fda4fe7c5fa20f72ffab2
3 files changed
tree: af29ee637582693f50aaa4e1e05a5385f26c8450
  1. bindings/
  2. cmake/
  3. docs/
  4. examples/
  5. include/
  6. lib/
  7. runtime/
  8. test/
  9. tools/
  10. unittests/
  11. utils/
  12. www/
  13. .clang-format
  14. .clang-tidy
  15. .gitignore
  16. AreaTeamMembers.txt
  17. CMakeLists.txt
  18. INSTALL.txt
  19. LICENSE.TXT
  20. Maintainers.rst
  21. NOTES.txt
  22. README.md
README.md

C language Family Front-end

Welcome to Clang.

This is a compiler front-end for the C family of languages (C, C++ and Objective-C) which is built as part of the LLVM compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read the relevant websites. Here are some pointers: