Un-ignore test_timeout, upgrade wiremock to 0.3

Support exponential backoff in check_real #1

Actions improvements: add rustfmt and clippy checks, run tests

Add exclude private URLs feature

This makes the test code shorter and more readable.

The exclusion is currently based on IP addresses, as specified by inputs.
We support IPv4 and IP...

This lets extract the host IP address, if defined for a website.
Mail addresses are not supported.

Show the progress interactively with progress bar and in-flight requests (--progress)

Use action-rs Actions instead

Needed multi-value args (with values accumulated into a vec)
for excluded urls

This is a preparation for easier async execution