DAS-2280: Merge TRANSPARENT_IDX and NODATA_IDX to increase available …

[flamingbear]

Description

Merges two similar indices into one.

TRANSPARENT_IDX is removed and NODATA_IDX is used instead.
TRANSPARENT_RGBA is replaced with NODATA_RGBA which has the same value.
The number of available colors is increased from 254 to 255 (indices:0 to 254).

There is a regression update that will show the only change in the output png images is that values that were 254 with color value (0,0,0,0) are now 255 with color value (0,0,0,0).

Jira Issue ID

DAS-2280

Local Test Steps

Pull this image, build and run the tests, deploy to Harmony-In-A-Box for verifying the regression:

❯ ./bin/build-image && ./bin/build-test &&  ./bin/run-test

PR Acceptance Checklist

• Jira ticket acceptance criteria met.
• CHANGELOG.md updated to include high level summary of PR changes.
• docker/service_version.txt updated if publishing a release.
• Tests added/updated and passing.
• Documentation updated (if needed).

[lyonthefrog]

I reviewed the code for these small changes and noticed a couple things that are likely non-issues, but wanted to double check. The unit tests pass.