Project files: Add upload helpers

[iLLiCiTiT]

Changelog Description

Add helper methods for project file upload.

Additional information

Noticed we have download but not upload. Idea came from community question asking why upload_file does not work, and it is because the endpoint expects to use POST method instead of PUT.

Testing notes:

1. Project file can be easily uploaded.

[BigRoy]

import ayon_api

filepath = r"C:\Users\User\Downloads\amazing.json"
print(ayon_api.upload_project_file("test", filepath=filepath))

Gives:

Traceback (most recent call last):
  File "C:\Users\User\AppData\Roaming\JetBrains\PyCharm2025.3\scratches\ayon_api_upload_project_file.py", line 6, in <module>
    print(ayon_api.upload_project_file("test", filepath=filepath))
  File "C:\roydev\dev\ayon-python-api\ayon_api\_api.py", line 1022, in upload_project_file
    return con.upload_project_file(
  File "C:\roydev\dev\ayon-python-api\ayon_api\server_api.py", line 1546, in upload_project_file
    return self.upload_file(
  File "C:\roydev\dev\ayon-python-api\ayon_api\server_api.py", line 1862, in upload_file
    return self.upload_file_from_stream(
  File "C:\roydev\dev\ayon-python-api\ayon_api\server_api.py", line 1813, in upload_file_from_stream
    return self._upload_file(
  File "C:\roydev\dev\ayon-python-api\ayon_api\server_api.py", line 1769, in _upload_file
    response.raise_for_status()
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\models.py", line 1024, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: http://127.0.0.1:5000/api/projects/test/files

Server creates logs:

2026-02-26 21:40:29 ERROR   api.server                 | Request validation error in [POST] /api/projects/test/files
2026-02-26 21:40:29     traceback:
2026-02-26 21:40:29       x-file-name: field required

Hence the lack of the x-file-name header is the issue?