fix: collect metrics to help analyze performance problems

[rix0rrr]

This PR changes telemetry to help diagnose and address performance problems.

The effective changes are as follows:

• We are seeing slow synth times.
  • Log the total number of assemblies and stacks to correlate and segment synth times and stack counts (is the relationship linear/nonlinear, are slow synth times due to huge applications, ...)
  • Log the (guessed) implementation language, to see if synth times behave differently between languages, if startup times make a lot of difference, etc.
• We are concerned about the time needed for agents to produce a successful CDK application.
  • Try to determine whether we are currently being run by an agent so we can segment on that.
  • Log the counts of warnings and errors, to see if deployment failure is or can be preceded/prevented by better error reporting at synth time.
• The library version we were collecting was a rough guess, do a better one once we have accurate information.
• Count the number of resources in a stack to correlate and segment deployment times by resource count.

For consistency, the same counters changes are being made to toolkit-lib, even though those counters aren't being consumed by anything.

---

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

[codecov-commenter]

Codecov Report

❌ Patch coverage is 71.73913% with 65 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.34%. Comparing base (da376fd) to head (a12cc87).

Files with missing lines	Patch %	Lines
packages/aws-cdk/lib/cli/util/guess-language.ts	42.62%	35 Missing ⚠️
packages/aws-cdk/lib/cli/util/guess-agent.ts	55.88%	13 Missing and 2 partials ⚠️
packages/aws-cdk/lib/cli/cli.ts	40.00%	9 Missing ⚠️
packages/aws-cdk/lib/cli/telemetry/session.ts	94.11%	4 Missing ⚠️
packages/aws-cdk/lib/cli/cdk-toolkit.ts	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1124      +/-   ##
==========================================
- Coverage   87.71%   87.34%   -0.37%     
==========================================
  Files          72       74       +2     
  Lines       10116    10329     +213     
  Branches     1337     1371      +34     
==========================================
+ Hits         8873     9022     +149     
- Misses       1217     1279      +62     
- Partials       26       28       +2     

Flag	Coverage Δ
suite.unit	87.34% <71.73%> (-0.37%)	⬇️

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