[LS] Add FVM stdlib to Flow Integration

[jribbink]

Closes #331

Description

Adds option to LS to accept additional stdlib values. This option is used by flow integration to provide FVM-native stdlib values (e.g. InternalEVM contract right now... others in future?)

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
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[jribbink]

I wasn't able to add the InternalEVM Contract to the WASM build unfortunately. Various downstream dependencies from the InternalEVM value declaration in flow-go (related to go-ethereum) do not build in WASM due to x/sys dependency, so it wasn't possible to import the FVM stdlib to the WASM build as a result.

I think this probably means that certain refactoring needs to be done in flow-go in order to avoid these dependencies... but not really sure how easy this is.

[turbolent]

Nice!