Adjust string splitting function

[weartist]

This commit fixes an issue where the string splitting function was handling characters in the input string improperly. We adjusted the use of the take_while function to calculate the length of the numeric prefix, rather than directly splitting the string, thus correctly splitting the string into a numeric prefix part and the remaining part

Release Notes:

• Fixed project panel Expand folder display error #9729 and Folders started with name combined number and characrter look like they are overlapping  #10193

[mikayla-maki]

Thank you!

[JosephTLyons]

Hey @weartist, can you make sure that you keep the release notes section at the end of every PR and to fill it out? We have a script that runs on Wednesday that looks specifically for this section when building the release notes - when it gets removed, we have to hunt down these pull requests and build the release notes by hand.

Release Notes:

- Added/Fixed/Improved ... ([#<public_issue_number_if_exists>](https://github.com/zed-industries/zed/issues/<public_issue_number_if_exists>)).

Here's an example of it being filled out:

• Send along diagnostics when requesting code actions #10281

[weartist]

Hey @weartist, can you make sure that you keep the release notes section at the end of every PR and to fill it out? We have a script that runs on Wednesday that looks specifically for this section when building the release notes - when it gets removed, we have to hunt down these pull requests and build the release notes by hand.

Release Notes:

- Added/Fixed/Improved ... ([#<public_issue_number_if_exists>](https://github.com/zed-industries/zed/issues/<public_issue_number_if_exists>)).

Here's an example of it being filled out:

• Send along diagnostics when requesting code actions #10281

No problem