[llvm-debuginfo-analyzer] Calculate unique offset for CodeView elements.

[CarlosAlbertoEnciso]

Extracted from llvm/tools/llvm-debuginfo-analyzer/README.txt

In order to have the same logical functionality as the ELF Reader, such
as:

• find scopes contribution to debug info
• sort by its physical location

The logical elements must have an unique offset (similar like the DWARF
DIE offset).

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: Carlos Alberto Enciso (CarlosAlbertoEnciso)

Extracted from [llvm/tools/llvm-debuginfo-analyzer/README.txt](https://github.com/llvm/llvm-project/blob/main/llvm/tools/llvm-debuginfo-analyzer/README.txt)

In order to have the same logical functionality as the ELF Reader, such
as:

• find scopes contribution to debug info
• sort by its physical location

The logical elements must have an unique offset (similar like the DWARF
DIE offset).