Use an ObjectWriter-based PE writer for crossgen2

[jkoritzinsky]

Today, crossgen2 uses its own PE builder built on top of System.Reflection.PortableExecutable. However, this implementation ends up manually redoing the vast majority of the features System.Reflection.PortableExecutable provides manually to support a number of edge cases that the library does not provide. Additionally, we plan to introduce a ReadyToRun format based on Mach-O (see #120065). There is no library like System.Reflection.PortableExecutable with a similar API that we could use for the Mach-O format, so we will either need to add some parallel path or move the PE path to something that can be shared with the Mach-O support.

For NativeAOT's ILCompiler, we use an ObjectWriter library based loosely around LibObjectFile to enable us to write COFF, ELF, and Mach-O objects. This library provides a consistent API for all three formats.

This PR changes crossgen2 to use a PE writer based on the COFF object writer from our ObjectWriter library. Additionally, this PR adds a number of features to the ObjectWriter library to support various constructs that are necessary for emitting a ReadyToRun image (symbol ranges, node size "relocs", deterministic file checksums, etc.).

This should make completing #120065 much easier as the vast majority of the "How do we emit code/data correctly so we can meet Apple's requirements?" question is already met by the MachObjectWriter in the ObjectWriter library, leaving a much smaller tail of work when adding support for it.

[jkoritzinsky]

/azp run runtime-coreclr r2r-extra, runtime-coreclr r2r, runtime-coreclr crossgen2, runtime-coreclr crossgen2 outerloop, runtime-coreclr crossgen2-composite

[azure-pipelines]

Azure Pipelines successfully started running 5 pipeline(s).

[jkoritzinsky]

My analysis of the failures:

crossgen2-composite is in main: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1173552&view=ms.vss-test-web.build-test-results-tab

r2r-extra: There's inconsistent occurrences of flaky tests like the ones I'm seeing here (stackoverflowtester in particular shows up quite a bit).

The TestReadyToRun_Libraries runs were broken due to an infra issue. Running them again now.

[jkoritzinsky]

/azp run runtime-coreclr crossgen2

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[davidwrighton]

Looks good. I have a few issues I'd like to see you address/file a bug for, but otherwise thumbs up

[agocke]

LGTM although I see a few FIXME comments. Might be worth having bugs for those

[jkoritzinsky]

/ba-g Windows arm64 queue is currently dead.