[CON-251] Newly created files aren't automatically visible in the @ files dropdown

[sestinj]

Before submitting your bug report

• I believe this is a bug. I'll try to join the Continue Discord for questions
• I'm not able to find an open issue that reports the same bug
• I've seen the troubleshooting guide on the Continue Docs

Relevant environment info

- OS:*
- Continue:*
- IDE:*

Description

Solution is an onDidCreateFile listener event like here that we can implement in both VS Code and JetBrains, and which can be used both to update the @ files dropdown and to update codebase indexes. This would be a pretty useful detail to get right, and shouldn't be an overwhelmingly complicated change

To reproduce

1. Create new file
2. Go to input box, type @ file, then search for the newly created file
   Not there : (

Log output

No response

_CON-251