Push tag helper checksums into the compiler

[DustinCampbell]

Rather than compute tag helper checksums at the tooling layer, this change pushes checksums into the compiler. The biggest benefit of this is that tag helpers now use checksums to test for equality and produce hash codes. So, the old tag helper comparers can be completely deleted, and equality checks should get faster across the board.

[davidwengier]

I mainly looked at the tooling changes, but LGTM.

Just for my curiousity, does the checksum builder actually have to be shared? Or is it just to keep the builder and checksum class close to each other. I couldn't see anything in the PR but might have missed it.

[DustinCampbell]

Just for my curiousity, does the checksum builder actually have to be shared? Or is it just to keep the builder and checksum class close to each other. I couldn't see anything in the PR but might have missed it.

Is there a reason why it shouldn't be in the shared project? It's a general mechanism for building SHA-256 checksums. I don't see a reason they should be separated.

[davidwengier]

Is there a reason why it shouldn't be in the shared project?

No, not at all. I'm just wondering if I missed something in the PR, and there is a scenario where checksums still need to be created on the tooling side.

[DustinCampbell]

No, not at all. I'm just wondering if I missed something in the PR, and there is a scenario where checksums still need to be created on the tooling side.

I just figured that it was a generally useful type, so it was reasonable to go into the shared layer. It's not tied to tag helpers in anyway, and is useful for producing SHA-256 checksums of potentially any object.

[DustinCampbell]

/azp run

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