[Feature] Autoclose backticks and asterisks in code editor

[chang]

Continuing the discussion in #1392 -

It would be a nice feature to have backticks and single/double asterisks close automatically, similar to brackets. When writing markdown, we frequently enclose expressions like so:

`code`
*italics*
**bold**

Also, the user should be able to highlight a block and press * key to surround the text with asterisks. Backticks already have this behavior.