Offer to test additional URLs and the SSO

[tituspijean]

Initial wording of the issue

Apps may require to test the accessibility of multiple URLs, let's list them and have the package check try them.

• Use case: Ghost requires to build separately the blog and the admin frontends.
  The current check only tries the main URL, not the admin one.

• (Wild) Use case: test connectivity of VPNs?

Discussed YunoCamp 2024 with @alexAubin

Example of tests.toml wording:

[curl]
index.logged = true #should the user be logged in for this test?
index.url = "/"
index.method = "GET" #method: GET, POST, ...
index.args = "" #list of args for POST requests
index.body= "" #list of args for POST requests
index.header = "" #a header to inject
index.expected_pattern = "" #a regex, that allows for __VARIABLE__ substitution, especially for username, full display name...
index.expected_return_code = 200
index.expected_header = ""
index.expected_cookie = ""