Add github workflows for ci

[badshah400]

The following five workflows are set up to build and install O2SCL as a shared library, and then run make check:

• openSUSE Tumbleweed i386: Fast suite of tests (make check fails).
• openSUSE Tumbleweed x86_64: Fast suite of tests (successful).
• openSUSE Tumbleweed x86_64: Full suite of tests (make check fails).
• Ubuntu x86_64: Fast suite of tests (successful).
• Ubuntu x86_64: Full suite of tests (successful).

All tests are configured to build with python bindings disabled as this cannot be currently tested in this set-up anyway. Where possible ccache is used to speed up repeated compilation of time-taking make and make check.

[awsteiner]

I'm approving these, but I will probably not be able to resist the urge to edit them a bit. Let me know if your process has requirements on these workflows (e.g. their yaml filename, format, or output) which you want me to obey.

[badshah400]

No problem, feel free to edit it to your liking. I felt like these are mere starting points myself. Thanks for the quick merge.