Add reconfigure flow to ntfy integration

[tr4nt0r]

Proposed change

Adds a reconfigure flow to the ntfy integration.

There are 2 possible reconfigure flows:

• If a config entry is configured without credentials, reconfigure will allow to add authentication to the config entry. Either by entering credentials, a token will be created automatically, or by entering an existing token directly.
• If a config entry configured with a username, reconfigure will allow to update the access token, either by entering a password, the new token will be created automatically or by entering the token directly. The username cannot be updated.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [x] New feature (which adds functionality to an existing integration)
• [ ] Deprecation (breaking change to happen in the future)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [ ] Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
• [x] There is no commented out code in this PR.
• [x] I have followed the development checklist
• [x] I have followed the perfect PR recommendations
• [x] The code has been formatted using Ruff (ruff format homeassistant tests)
• [x] Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• [ ] Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• [ ] The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• [ ] New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• [ ] For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.

To help with the load of incoming pull requests:

• [ ] I have reviewed two other open pull requests in this repository.

[hanwg]

The config flow could have been more user friendly.

I think it will be better to split the flow into 3 steps:

• choose authentication type step - this is the initial step which will continue to either the username/password step or the api token step depending on what option the user selects.
• username/password step
• api token step

[home-assistant[bot]]

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[tr4nt0r]

@zweckj I think you forgot to merge this one 😬