Added test_version parameter to cli

[abdullahzen]

Changes made:

• Added test_version parameter to cli when used with build --test to produce the test artifact with a desired numbered version rather than using the commit_count which is always 0.
• Kept the default value for the "test_version" as 0.

Fixes #332

[xsuchy]

-1 from me.

Commit_count is the number of commits since the last tagged version. When your workflow is git-commit/tito-build/rpm -U then commit_count assures that package is always upgradable (every subsequent release is bigger than the previous one). Although this breaks when you git commit --amend -a

[abdullahzen]

@xsuchy
Thank you for taking the time. I do agree with you but I was adding a feature as requested in the issue #332 where he mentions a use case for overriding the version.
I do see where I went wrong tho. I should set the default to commit_count and if test_version is passed, it'll override the commit_count. Thank you for clarifying that for me 👍
Do you believe that would be a good idea to allow both ways and let the test_version only override the count if test_version is set?

[xsuchy]

+1 LGTM now.

[abdullahzen]

Thank you!