Surround selected text with typed backtick or single quote in markdown fields

What does this MR do?

When selecting text in a markdown field, typing a backtick or single quote should surround the selected text with that character.

This MR supports the following:

• ` backtick
• ' single quotes
• " double quotes
• _ underscore (wraps the text in the markdown italic character)
• * asterisk (wraps the text in the markdown bold characters, **)
• [ brackets
• < angle brackets
• ( parentheses

It's only targeted to our standard markdown fields (issue/mr descriptions, notes, ect). Since blobs are handled using the Ace editor, it already has some limited support (quotes, brackets, etc). If additional support it needed, we should probably consider extending the Ace editor.

Related to: #23980 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team