Convert Unit Test Library from `bash_unit` to `shellspec`

[ReedClanton]

Description

Remove bash_unit tests and GitHub actions. Add unit tests of output() and related util code.

High Level Solution Description

Learn shellspec and implement enough unit tests to be able to say I learned it. Also remove old bash_unit unit tests.

Alternative Solution(s)

None

Blocked By

• None

Blocking

• Get shellspec Unit Tests Running on GitHub Runner #24
• Create Unit Tests of shellName() and Any Util Code #32
• Create Unit Tests of log() and Any Util Code #36
• Create Unit Tests of output() and Any Util Code #38
• Create Unit Tests of backUp() and Any Util Code #39
• Create Unit Tests of checkRequiredOpts() and Any Util Code #40

Related Issue(s)

• Get shellspec Unit Tests Running on GitHub Runner #24
• Create Unit Tests of shellName() and Any Util Code #32
• Create Unit Tests of log() and Any Util Code #36
• Create Unit Tests of output() and Any Util Code #38
• Create Unit Tests of backUp() and Any Util Code #39
• Create Unit Tests of checkRequiredOpts() and Any Util Code #40

Additional Context

This is going to be a bear.