Implement ftruncate function (IDFGH-6641)

[igrr]

Is your feature request related to a problem? Please describe.

truncate function was requested in #1980 and implemented in c77f84e, however the related ftruncate function was not implemented.

Describe the solution you'd like

• Implement ftruncate function in VFS
• Implement ftruncate in FAT VFS

Describe alternatives you've considered

Instead of having both truncate and ftruncate functions in VFS interface, VFS layer could supply a truncate implementation and only require ftruncate to be implemented by the VFS driver. The VFS layer could implement truncate using driver's open, ftruncate, close methods. This, however, would be a breaking change since we would have to replace truncate with ftruncate in the VFS interface.

Additional context

Requested in a comment to the closed issue: #1980 (comment)
Issues that would be solved by implementing this:

• undefined reference to `ftruncate' joltwallet/esp_littlefs#57
• https://github.com/kuba--/zip/issues/231

[Rajssss]

@igrr any update on this?

[MabezDev]

FYI the Rust standard library relies on ftruncate being available, first reported here: esp-rs/rust#100.