Refactor and centralize file mimeType integrity check and sanitization (#20889)

# Introduction
closes https://github.com/twentyhq/private-issues/issues/484

This PR refactors the writeFile API to never expect to be passed a
mimetype, its extract is done programmatically low level so any callers
will pass through
Same for the file sanitization

## IANA override
Disclaimer for consistency we existing behavior we wanted to always have
`application/typescript`
- should we rather consider fallbacking to octect-steam instead ?
- Any pulbic assets that has .ts will now also fallback to
`application/typescript` instead of the official IANA

## Integration
Added coverage

packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/services/prefill-front-component.service.ts

@@ -83,7 +83,6 @@ export class PrefillFrontComponentService {
         fileFolder: FileFolder.Source,
         resourcePath: sourceComponentPath,
         sourceFile: sourceFile.content,
-        mimeType: 'application/typescript',
         settings: {
           isTemporaryFile: false,
           toDelete: false,
@@ -97,7 +96,6 @@ export class PrefillFrontComponentService {
         fileFolder: FileFolder.BuiltFrontComponent,
         resourcePath: builtComponentPath,
         sourceFile: builtFile.content,
-        mimeType: 'application/javascript',
         settings: {
           isTemporaryFile: false,
           toDelete: false,