feat: check file type with validation

[nahiyankhan]

This feature adds a check to make sure the selected file is of type text and not binary. If the user selects a filetype thats not allowed, a system modal shows an error.

[nahiyankhan]

@alexhancock @lily-de - I wonder if this is restrictive in the sense that the wrong file sent to goose does give back some feedback on why it might not work. I noticed that for .docx or so - it suggests using a text extractor. Thoughts on whether goose should make a reasonable attempt or it's up to the user?

[lily-de]

@nahiyankhan i think if goose can reliably do it for docx it can try! sounds cool. does it start like programming something lol? i think that will freak non-devs out a bit 👻

[nahiyankhan]

@nahiyankhan i think if goose can reliably do it for docx it can try! sounds cool. does it start like programming something lol? i think that will freak non-devs out a bit 👻

It doesn't attempt by default - but does suggest options and whether I want to try them! I'll file it under future consideration for now