feat: add _typescript.configurePlugin workspace command

[mskelton]

This adds support for the _typescript.configurePlugin command which allows clients to dynamically update plugin configuration. This is useful when configuring global plugins which, since defined via the command line flags, cannot be configured the same way they might when defined in a local tsconfig.json file.

An example of this in Neovim which enables the typescript-styled-plugin with some configuration changes.

require("lspconfig").tsserver.setup({
  init_options = {
    plugins = {
      {
        name = "typescript-styled-plugin",
        location = "..."
      }
    }
  },
  on_init = function()
    local params = {
      command = "_typescript.configurePlugin",
      arguments = {
        "typescript-styled-plugin",
        {
          validate = false,
          emmet = {
            showExpandedAbbreviation = false
          }
        }
      },
    }
    
    client.request("workspace/executeCommand", params)
  end
})

[rchl]

Thanks