Support commas in variables

[jan-cerny]

This adds support for commas in variable values in the test
scenarios metadata in the variables key. For example:
# variables = sshd_approved_ciphers=ijkl158,sits,wwq-98,kl24

Fixes: #7553

[github-actions]

Start a new ephemeral environment with changes proposed in this pull request:

rhel8 (from CTF) Environment (using Fedora as testing environment)

Fedora Testing Environment

Oracle Linux 8 Environment

[codeclimate]

Code Climate has analyzed commit ec28ce8 and detected 2 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	2

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 42.7% (0.0% change).

View more on Code Climate.

[openshift-ci]

@jan-cerny: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-aws-rhcos4-moderate	ec28ce8	link	true	/test e2e-aws-rhcos4-moderate
ci/prow/e2e-aws-rhcos4-high	ec28ce8	link	true	/test e2e-aws-rhcos4-high

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