Escape keys

[ryangclark]

Implements escapeKeys as an enhancement to allow closing the inspector via a hotkey, as requested by #858.

By default, the escapeKeys are Backspace and Escape, though they can be configured via SVELTE_INSPECTOR_OPTIONS like the inspector's other hotkeys.

[dominikg]

thank you for working on this. Please run pnpm generate:types in the inspector directory and commit/push the changes. This is needed because we ship the source to npm directly without an additional build step.

[ryangclark]

Types generated.

Thanks for your review, and for all your previous work.