Support for CLANGPDB in AARCH64

[cfernald]

To allow for more portable compiling and support using COFF based debug and development tools, support for CLANGPDB in AARCH64 would be largely beneficial.

I have experimented and got this working for MdeModulePkg but with a fair number of hacks, so far there are a following issues.

1. The toolsdef does not contains definitions for CLANGPDB in AARCH64
2. Many of the .S files and macro definitions use the ELF format of the .type and .size assembly directives
3. Various compiler warning issues.

The commit for this experiment can be found here: https://github.com/cfernald/mu_basecore/commit/9587e16f22b3cac8722d21086a45e128af4cf2b4

[github-actions[bot]]

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