Closes #18228

We parse local clickable links by looking for start/end based on
whitespace. However, this means that we don't catch links which are
embedded in parenthesis, such as in markdown syntax:
`[here's my link text](./path/to/file.txt)`

Parsing strictly against parenthesis can be problematic, because
strictly-speaking, files can have parenthesis. This is a valid file name
in at least MacOS:
`thisfilehas)parens.txt`

Therefore, this change adds a small regex layer on top of the filename
finding logic, which parses out text within parenthesis. If any are
found, they are checked for being a valid filepath. The original
filename string is also checked in order to preserve behavior.

Before:


https://github.com/user-attachments/assets/37f60335-e947-4879-9ca2-88a33f5781f5

After:



https://github.com/user-attachments/assets/bd10649e-ad74-43da-80f4-3e7fd56abd86



Release Notes:

- Improved link parsing for cases when a link is embedded in
parenthesis, e.g. markdown