use proper text editor instead of textarea element

[samuelstroschein]

The pattern editor uses an input element right now. Use an editor like https://github.com/facebook/lexical in the future to render placeholders and not only text.

Open questions

• What editor SDK to use (prosemirror, lexical, monaco)?
• What features should the editor have?

Additional information

inlang has been designed to enable a proper editor for messages with the AST. Read RFC-001 for a refresher.

[samuelstroschein]

Using a proper text editor likely also mitigates performance bottlenecks. The shoelace textarea component take an exorbitant amount of time to calculate its size

[samuelstroschein]

@NilsJacobsen @NiklasBuchfink oh look I ran into the recent performance issues in January already.

[samuelstroschein]

Shipped by @NiklasBuchfink @NilsJacobsen in #602