Consolidate `fs.written` and `fs.write`

[KernelDeimos]

fs.written was added to provide an event that's fired after the entire contents of a file has been written. The previously-existing fs.write does not wait for upload. It was realized that none of the listeners to fs.write interact with the file stream, so we can make fs.write behave the way fs.written currently does and remove the fs.written event.

This PR requires updating WorkerService:

puter/src/backend/src/services/worker/WorkerService.js

Line 93 in 85a0f71

svc_event.on('fs.written.file', async (_key, data, meta) => {

Workers need to be fully tested after these changes.

[KernelDeimos]

@XiaochenCui (tag for assigning)

[XiaochenCui]

thanks, I'll take this one

[XiaochenCui]

we gonna making it clear later