Update internal file keeping on file move event

[kanej]

The language server's internal state maintains an index of each solidity file and the project it is related to. We need to update the metadata on a file rename event occurring in the project.

See the rename event in the specification: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_didRename

Consideration should be given to dealing with existing diagnostics. The diagnostics should migrate with the rename.

Similarly we should update the metadata and diagnostics on file delete.

Part of #387