[0.75] Fix file upload with FormData

[foyarash]

Target Branch(es)

0.75

Link to commit or PR to be picked

facebook/react-native#46543

Description

0.74 introduced an issue to FormData that breaks file upload with FormData, where the Content-Disposition header does not respect the required format. The changes introduced in the PR fixes that.

[blakef]

We can't land this in 0.75 until it lands in main. Skipping for 0.75.4.

[cipolleschi]

✅ Picked