Only sends a `textDocument/documentHighlight` request when on an identifier

<!-- ⚠️⚠️ Do Not Delete This! bug_report_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- 🕮 Read our guide about submitting issues: https://github.com/microsoft/vscode/wiki/Submitting-Bugs-and-Suggestions --> <!-- 🔎 Search existing issues to avoid creating duplicates. --> <!-- 🧪 Test using the latest Insiders build to see if your issue has already been fixed: https://code.visualstudio.com/insiders/ --> <!-- 💡 Instead of creating your report here, use 'Report Issue' from the 'Help' menu in VS Code to pre-fill useful information. --> <!-- 🔧 Launch with `code --disable-extensions` to check. --> Does this issue occur when all extensions are disabled?: Yes <!-- 🪓 If you answered No above, use 'Help: Start Extension Bisect' from Command Palette to try to identify the cause. --> <!-- 📣 Issues caused by an extension need to be reported directly to the extension publisher. The 'Help > Report Issue' dialog can assist with this. --> - VS Code Version: 1.57.1 VSCode doesn't seem to send a `textDocument/documentHighlight` request when the cursor isn't on an identifier(whatever this means to vscode). The LSP documentation doesn't state that this request should only be sent in that case though. > The document highlight request is sent from the client to the server to resolve a document highlights for a given text document position. > https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_documentHighlight We ran into this in rust-analyzer when trying to highlight exit points, which in rust can have the form of a simple `?` character. So having the cursor on this character currently can't trigger the highlight. https://github.com/rust-analyzer/rust-analyzer/pull/9375