* Store checksums as a first-class piece of data in our persistence layer.

* Include the format version in the persistence checksum.

* Move symbol tree over to the checksym approach.

* Update sql persistence service to use checksums.

* Update tests.

* Fix wrapper.

* Remove projects.

* Add tests with checksums.

* Add more tests.

* Add test.

* Add comments.

* Simplify.

* Simplify.

* Revert.

* Revert.

* Revert.

* Add comment.

* Add comment.

* Add comment.

* Rev the checksum.

* Add comment.

* Add comment.

* Add comment.

* Add comment.

* Simplify.

* merge

* rename

* No allow checksym creation

* Rename

* cache strings

* simplify

* Remove optional params

* Update src/Workspaces/Core/Portable/FindSymbols/SyntaxTree/SyntaxTreeIndex_Persistence.cs
Co-Authored-By: NAndrew Harper <aharper@breuer.com>

Co-Authored-By: NCyrusNajmabadi <cyrus.najmabadi@gmail.com>

Co-Authored-By: NCyrusNajmabadi <cyrus.najmabadi@gmail.com>

Co-Authored-By: NCyrusNajmabadi <cyrus.najmabadi@gmail.com>

* some code clean up and added some code instruments to make perf investigation easier

* changed lambda to local function and addressed feedback

made VS not crash on invalid dll reference (BadImageFormatException). especially for find all reference cache generation (#24452)

this basically prevent symbol info indexer from creating/calculating same checksum again and again for every documents in the solution.

this should make it to do it only once per project rather than document, and only update it when there is a change in the project.