This form can be used to create a new resource or to update an existing one.
To update an existing resource, we need to send a PATCH request to the server.
This commit adds ability to send PATCH requests to the backend.
HTML forms unfortunately do not support PATCH requests. There are 2 common ways
to work around this limitation:
1. Send regular `POST` request with special hidden input and backend can handle
the request as if it is `PATCH` based on the hidden input field.
2. Use JavaScript to change the request method before submitting the form
I opted for the second approach because it fits to RESTful semantics better.
Also the proposal for extending HTML form methods lists additional drawbacks
regarding use of hidden input fields [1].
[1] https://alexanderpetros.com/triptych/form-http-methods#hidden-input-hack
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