[ENH] deduplicate dependency checkers and isolate soft dependency imports by using skbase

[fkiraly]

This PR deduplicates dependency checkers by using skbase, which is currently an implied dependency, and which contains equivalent functionality.

This improves maintainability of the dependencies module through deduplication.

Importantly, it also helps with soft dependency isolation because the skbase dependency checker does not actually import all modules while checking - making future work on reducing impact of soft dependencies easier.

In line with best practice, packaging and scikit-base are added as dependencies to pyproject.toml, since there are now direct imports.

No deprecation or change period is necessary, since both packages were already implied by core dependencies.

Requires pycaret#4124 because we are using pyproject.toml.

[amotl]

The patch has been submitted to upstream. Thanks a stack!

• [ENH] deduplicate dependency checkers and isolate soft dependency imports by using skbase pycaret/pycaret#4141