Add support for schema overrides

[rchl]

By default this workflow will look for sublime-package.overrides.json that can look like this:

{
    "add": {
        "rust-analyzer.terminusAutoClose": {
          "default": false,
          "description": "Whether or not to automatically close terminus panel/tab upon completion.",
          "type": "boolean"
        },
        "rust-analyzer.terminusUsePanel": {
          "default": false,
          "description": "Whether or not to spawn a panel at the bottom, or a new tab.",
          "type": "boolean"
        }
    },
    "remove": [
        "rust-analyzer.debug.buildBeforeRestart",
        "rust-analyzer.debug.engine",
        "rust-analyzer.debug.engineSettings",
        "rust-analyzer.debug.openDebugPane",
        "rust-analyzer.debug.sourceFileMap",
        "rust-analyzer.initializeStopped",
        "rust-analyzer.restartServerOnConfigChange",
        "rust-analyzer.runnables.askBeforeUpdateTest",
        "rust-analyzer.runnables.problemMatcher",
        "rust-analyzer.server.extraEnv",
        "rust-analyzer.server.path",
        "rust-analyzer.showDependenciesExplorer",
        "rust-analyzer.showRequestFailedErrorNotification",
        "rust-analyzer.showSyntaxTree",
        "rust-analyzer.showUnlinkedFileNotification",
        "rust-analyzer.statusBar.clickAction",
        "rust-analyzer.testExplorer",
        "rust-analyzer.trace.extension",
        "rust-analyzer.trace.server"
    ],
    "transform": [
        "walk(if type == \"object\" then with_entries(if .key == \"description\" then .key = \"markdownDescription\" else . end) else . end)",
        "walk(if type == \"object\" then with_entries(if .key == \"enumDescriptions\" then .key = \"markdownEnumDescriptions\" else . end) else . end)"
    ]
}

It will also print the full settings schema and sublime-settings settings to make it easier to replace everything in one go instead of merging manually.

Next step I guess is to automate it so that the changes are merged to relevant files by the bot.