Expand PerfMap format to support metadata for symbol indexation (#53792)

Expand PerfMap format to support metadata for symbol indexation (#53792)

I have expanded the PerfMap format produced by Crossgen2 and
R2RDump to produce metadata in form of pseudo-symbol records with
high addresses. In this version I have implemented four metadata
entries - output GUID, target OS, target architecture and perfmap
format version number.  I have verified for System.Private.CoreLib
and for the composite framework that Crossgen2 and R2RDump
produce identical metadata.

To facilitate a smooth transition to the new perfmap format, in
accordance with Juan's suggestion I have introduced a new command-line
option to explicitly specify the perfmap format revision. As of today,
0 corresponds to the legacy Crossgen1-style output where the
perfmap file name includes the {MVID} section, perfmap format #1
corresponds to current Crossgen2 with its new naming scheme.
As of today there are no differences in the file content.

Thanks

Tomas