Added filter to allow for changing the output of die_on_login

[coperator]

Motivation

Error messages during login should be shown in a helpful way to the enduser. We want to add further information to the wp-auth0 error message, which are specific for our setup. The filter allows a modification of the shown html, similar to how it is already done for the email verification prompt.

Changes

• Changed method die_on_login in class WP_Auth0_LoginManager to apply a filter on the html output.

Testing

No tests added & modified.

• I included manual testing steps above, if applicable
• This change adds unit test coverage
• This change has been tested on the latest version of the platform/language or why not

Checklist

• I read Auth0's general contribution guidelines?
• I read Auth0's code of conduct guidelines
• All existing and new tests complete without errors
• All code quality tools/guidelines in the Contribution guide have been run/followed
• All relevant assets have been compiled as directed in the Contribution guide, if applicable
• All active GitHub CI checks have passed

[joshcanhelp]

Thank you @coperator, this looks great!

Would you mind writing a few unit tests for this? We already have a test suite for this class and you can see an example of a filter output test here (this is also the suite to add it in):

https://github.com/auth0/wp-auth0/blob/master/tests/testLoginManager.php#L65

... and an example of checking that the hook is actually there:

https://github.com/auth0/wp-auth0/blob/master/tests/testProfileChangePassword.php#L76

You'll need to add the HookHelpers trait to the TestLoginManager class.

Not required to merge it but will save some trouble later.

Thanks again!

[coperator]

Yeah, sure, I can do this. Although, currently I'm very busy. Plan to this in the next weeks.

[joshcanhelp]

No problem @coperator.I'll approve and merge this now so we have it for the next release. If you can come back and put through a PR for the tests later, that would be appreciated.

[joshcanhelp]

LGTM!