Previously, it was necessary to attach on of the three "stability"
jsdoc tags (`@stable`, `@deprecated` or `@experimental`) to each
public API export.
To ensure that the public API was correctly tagged, the `ts-api-guardian`
would check that one of these tags appeared on every public export.
Now the doc-gen is able to compute that a code item is stable if
it does not contain the `@experimental` nor `@deprecated` tags.
Therefore there is no need to provide the `@stable` tag any more; and
this tag has now been marked as deprecated - i.e. it should not be used.
The ts-api-guardian has been modified in this commit so that it no longer
warns/fails if the `@stable` is missing.
PR Close#23176
Also use it to test the public API for core and common
Once we have an ng_package for every package, we can remove
the npm dependency on ts-api-guardian and the gulp-based
public api check.
PR Close#22544
Pete Bacon Darwin
Alex Eagle