Add public API event for kernel post-initialization #17429

Job	Run time
Build VSIX	1m 24s
Lint	1m 56s
cancel_previous_runs	8s
Type Script Tests (ubuntu-latest, ts-unit)	1m 36s
Type Script Tests (windows-latest, ts-unit)	6m 4s
Tests (raw, python, 3.10, ^[^@]+$\|@mandatory\|@kernelCore\|@python\|@jupyter, ubuntu-latest)	5m 37s
Tests (raw, python, 3.10, @widgets, ubuntu-latest)	4m 44s
Tests (raw, python, 3.10, @iw, ubuntu-latest)	3m 48s
Tests (raw, python, 3.10, @webview\|@export\|@lsp\|@variableViewer, ubuntu-latest)	4m 18s
Tests (raw, python, 3.10, @debugger, ubuntu-latest)	3m 28s
Tests (remote, python, 3.10, ^[^@]+$\|@mandatory, ubuntu-latest)	3m 46s
Tests (web, python, 3.10, ^[^@]+$\|@mandatory, ubuntu-latest)	2m 42s
Tests (raw, python, 3.10, ^[^@]+$\|@mandatory, windows-latest)	8m 29s
Tests (raw, python, 3.10, @widgets, ubuntu-latest, 8)	5m 12s
Tests (remote, python, 3.10, @widgets, ubuntu-latest, 8)	5m 39s
Tests (raw, conda, 3.10, ^[^@]+$\|@mandatory\|@python, ubuntu-latest)	3m 21s
Tests (raw, noPython, @nonPython, ubuntu-latest)	1m 41s
Tests (remote, python, 3.10, @kernelCore, ubuntu-latest)	4m 13s
Smoke tests (ubuntu-latest, 3.10)	1m 31s
Smoke tests (windows-latest, 3.10)	4m 39s
Smoke tests (macos-latest, 3.10)	1m 48s
	1h 16m 4s

Provide feedback