feat: make undo and redo as ProseMirror commands

[ocavue]

This PR changes the function signature of undo and redo. The second parameter dispatch is now optional. By doing that, undo and redo match ProseMirror command definition.

A command function takes an editor state, optionally a dispatch function that it can use to dispatch a transaction and optionally an EditorView instance. It should return a boolean that indicates whether it could perform any action. When no dispatch callback is passed, the command should do a 'dry run', determining whether it is applicable, but not actually doing anything.
docs link

---

Some other changes included in this PR but not directly related to the feature above:

1. Add a PNPM workspace, so that the storybook can pick the current developing version of loro-prosemirror

2. Add type prefix when importing a TS type. This fixes the following Rollup error when building

   [!] RollupError: "LoroSyncPluginProps" is not exported by "src/sync-plugin.ts", imported by "src/index.ts".
   

3. Update tsconfig.json so that TypeScript can check the type prefix. Add a pnpm run lint script and run it in the CI workflow.

[ocavue]

There is no point calling dispatch when the function failed to execute the action (i.e. return false).

[zxch3n]

Thanks a lot! LGTM