bpo-43811: Test multiple OpenSSL versions on GHA (GH-25360)

bpo-43811: Test multiple OpenSSL versions on GHA (GH-25360)

The new checks are only executed when one or more OpenSSL-related files are modified. The checks run a handful of networking and hashing test suites. All SSL checks are optional. This PR also introduces ccache to speed up compilation. In common cases it speeds up configure and compile time from about 90 seconds to less than 30 seconds.

Signed-off-by: Christian Heimes <christian@python.org>