Complete SemanticTokensOptions definition

[gamebox]

Closes #47

Replacing go.lsp.dev/protocol with this repository and the following server capability:

var semanticTokensOptions = lsp.SemanticTokensOptions{
                WorkDoneProgressOptions: lsp.WorkDoneProgressOptions{
                    WorkDoneProgress: false,
                },
                Legend: &lsp.SemanticTokensLegend{
                    TokenTypes: SemanticTokenLegend,
                    TokenModifiers: []lsp.SemanticTokenModifiers{},
                },
                Range: false,
                Full: &lsp.SemanticTokensFullOptions{ Delta: false },
           }

I actually successfully register the SemanticTokensProvider capability with my client.

2024/01/01 09:42:33 [SERVER]: ==========================================
2024/01/01 09:42:33 [SERVER]: Received message for method "textDocument/semanticTokens/full"
2024/01/01 09:42:33 [SERVER]: ------------------------------------------

I know that there is some tagging to be added, and probably a todo for the empty interface.