Add ability to run ESLint (and other non-primary language server) code actions on format

[mrnugget]

This PR does two things to fix #4325:

1. It changes the way code_actions_on_format works to send the possibly configured code actions to all (and not just the primary) languages servers. That means configured code actions can now be sent to ESLint, tailwind, ... and other language servers.
2. It enables codeActionsOnSave by default for ESLint. That does not mean that by default we will run something on save, but only that we enable it for ESLint.

Users can then configure their Zed to run the eslint code action on format. Example, for JavaScript:

    {
      "languages": {
        "JavaScript": {
          "code_actions_on_format": {
            "source.fixAll.eslint": true
          }
        },
      }
    }

Release Notes:

• Added ability to run ESLint fixes when formatting a buffer. Code actions configured in code_actions_on_format are now being sent to all language servers connected to a buffer, not just the primary one. So if a user now sets "code_actions_on_format": { "source.fixAll.eslint": true } in their Zed settings, the source.fixAll.eslint code action will be sent to ESLint, which is not a primary language server. Since the formatter (prettier, or external commands, or another language server, ...) still runs, it's important that these code actions and the formatter don't clash. (#4325).

Demo:

screenshot-2024-02-28-13.31.27.mp4