feat(toolkit-lib): emit marker messages during actions

[mrgrain]

Introduces the new concept of "Message Spans" to connect multiple messages for toolkit sub-tasks like "synth" or "build-assets" together. A span consists of a number of messages that have the same span value.

At a minimum, a span is a pair of a start and an end message. Every end message also reports the elapsed time since the start of the span.

Message spans will allow integrators to more easily track the flow of "tasks" completed in the Toolkit.

Changes

• Refactors the previous Timer class to "Message Spans"
• Introduces a new registry for spans at the bottom of the existing messages registry. A span consists of a start and an end message maker.
• This PR makes use of the new IoHelper to provide a nicer API
• There is some more of type magic to ensure correct payloads, I don't think this can be tested further
• I also changed the message registry to be private again, we are not ready to have it as part of the public interface (this doesn't affect our packages)
• Made some improvements to the bundling of declaration files. It's currently really slow because it ends up scanning through A LOT of SDK types. Will look into this more in a follow-up PR.

Fixes aws/aws-cdk#33286

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[mrgrain]

All added messages are traces and won't show up in regular logging configurations (like our cli).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.86%. Comparing base (0c21495) to head (d14dbcb).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #219      +/-   ##
==========================================
+ Coverage   84.84%   84.86%   +0.01%     
==========================================
  Files         208      208              
  Lines       35564    35563       -1     
  Branches     4612     4612              
==========================================
+ Hits        30175    30179       +4     
+ Misses       5239     5237       -2     
+ Partials      150      147       -3     

Flag	Coverage Δ
suite.unit	84.86% <100.00%> (+0.01%)	⬆️

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[rix0rrr]

...and I would call this something like begin.

[mrgrain]

I kept the ioHelper.span(...).begin(...) approach. API looks nicer to me that way.

[mrgrain]

Bundling currently takes a while because the declaration bundling started to scan through sdk packages. I plan to fix/work-around/whatever, but in the meantime make this slightly faster by doing all work in parallel.

[mrgrain]

Needs to move to shared because it is used in payloads.