Support commands

[genericptr]

I believe we can use Lazarus code tool commands with this but I haven't studied it yet.

Represents a reference to a command. Provides a title which will be used to represent a command in the UI. Commands are identified by a string identifier. The recommended way to handle commands is to implement their execution on the server side if the client and server provides the corresponding capabilities. Alternatively the tool extension code could handle the command. The protocol currently doesn’t specify a set of well-known commands.

https://lsp.sublimetext.io/features/#server-commands
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#command

Example of a ST command (https://github.com/sublimelsp/LSP-TexLab/blob/master/LSP-TexLab.sublime-commands) which uses lsp_execute to send the command to workspace/executeCommand (https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_executeCommand)