Advanced grammar checking

[twocaretcat]

Is This New?

• I have read all available documentation (ex. README.md, CONTRIBUTING.md, external docs site, etc.)
• I have searched for existing issues
• I'm willing to implement this myself (optional)

What?

Additional enhancements for grammar checking integrated with Harper like:

• suggestions
• ignoring suggestions
• applying suggestions to text
• saving words to dictionary
• configurable linting rules

Why?

This will increase the utility of the app.

Alternatives

No response