feat(ado-improvements-1): Pipeline specific formatting

[DaveTryon]

Details

In #1048, it was pointed out that we have a requirement for pipeline-specific formatting. Summarizing from ADO docs and Workflow docs, we have the following matrix of formatting:

Concept	ADO	Workflow
error	##[error]	::error::
warning	##[warning]	::warning::
debug	##[debug]	::debug::
info	none	none
start group	##[group]	::group::
end group	##[endgroup]	::endgroup::

To this end, we've modified the Logger and LogLevel use the following API's, LogLevel, and generic tags:

Concept	Logger API	LogLevel	Generic tag from Logger
error	LogError	error	[error]
warning	LogWarning	warning	[warning]
debug	LogDebug	debug	[debug]
info	LogInfo	info	[info]
start group	StartGroup	group	[group]
end group	EndGroup	endgroup	[endgroup]

Then we create pipeline-specific stdout transformers (adoStdoutTransformer and ghStdoutTransformer) to convert the generic output to the pipeilne-specific output.

Motivation

Improve #950, also includes changes from #1048 (which need this infrastucture to work correctly)

Context

There is some duplicated code between adoStdoutTransformer and ghStdoutTransformer. There are probably opportunities to improve this, but since it was a very small part of the whole change, and since I was having build problems, I left that for another PR.

I had a few false starts on this, so trying to review this per commit might add confusion, not clarity.

Pull request checklist

• Addresses an existing issue: Needed for Task log output is too verbose, difficult to read #950
• Added relevant unit test for your changes. (yarn test)
• Verified code coverage for the changes made. Check coverage report at: <rootDir>/test-results/unit/coverage
• Ran precheckin (yarn precheckin)