feat(lint): add JavaScript plugin support

[bartlomieju]

This commit adds an unstable lint plugin API.

Plugins are specified in the deno.json file under
lint.plugins option like so:

{
  "lint": {
    "plugins": [
      "./plugins/my-plugin.ts",
      "jsr:@deno/lint-plugin1",
      "npm:@deno/lint-plugin2"
    ]
  }
}

The API is considered unstable and might be subject
to changes in the future.

Plugin API was modelled after ESLint API for the
most part, but there are no guarantees for compatibility.
The AST format exposed to plugins is closely modelled
after the AST that typescript-eslint uses.

Lint plugins use the visitor pattern and can add
diagnostics like so:

export default {
  name: "lint-plugin",
  rules: {
    "plugin-rule": {
      create(context) {
        return {
          Identifier(node) {
            if (node.name === "a") {
              context.report({
                node,
                message: "should be b",
                fix(fixer) {
                  return fixer.replaceText(node, "_b");
                },
              });
            }
          },
        };
      },
    },
  },
} satisfies Deno.lint.Plugin;

Besides reporting errors (diagnostics) plugins can provide
automatic fixes that use text replacement to apply changes.

[dsherret]

LGTM!