fix: auto-complete for `$$` and `^^`

[AyushAgrawal-A2]

closes #10932

Changes:

• Fixes auto complete for ^^
• Fixes end cursor travel for $$

[andelf]

This is far more difficult to implement correctly:

• The normal case: typing two ^
• Select some text and type two ^ - this fails

[andelf]

Hold this when feat/db branch is merged.