Add minimal Docker setup to enable a build and test run

[kjsanger]

This setup is sufficient to build and run tests inside a VScode container. There is one test which fails inside a Docker container because it invokes the docker client itself. Fixing that is tech debt

[mksanger]

The apt repository only contains 4.3.0 (latest) iRODS-dev / icommands / runtime packages

[kjsanger]

The apt repository only contains 4.3.0 (latest) iRODS-dev / icommands / runtime packages

Not so, it has all the old ones, e.g. https://packages.irods.org/apt/pool/bionic/main/i/

You might have to set IRODS_VERSION to whatever package version they're using, if it's not just a basic x.y.z number.

[mksanger]

Is the failing test expected to hang? I get:

baton@294a95796d36:/workspace$ make check
Making check in src
make[1]: Entering directory '/workspace/src'
make[1]: Nothing to be done for 'check'.
make[1]: Leaving directory '/workspace/src'
Making check in .
make[1]: Entering directory '/workspace'
make[1]: Leaving directory '/workspace'
Making check in tests
make[1]: Entering directory '/workspace/tests'
make  check_baton
make[2]: Entering directory '/workspace/tests'
make[2]: 'check_baton' is up to date.
make[2]: Leaving directory '/workspace/tests'
make  check-TESTS
make[2]: Entering directory '/workspace/tests'
make[3]: Entering directory '/workspace/tests'

Which then hangs, and the only log message is Failed to open 'no_such_path': error 2 No such file or directory, which I assume is expected.

[kjsanger]

The whole test suite hangs? If so, no. That doesn't happen on Linux or Intel macOS.

[mksanger]

The hang was due to not running iinit before testing.