split into multiple workflows to speed up CI

[fgksgf]

Currently, the CI is time-consuming and will be triggered when make non-code changes.
So I split into multiple github action workflows for linting, unit testing and license checking, respectively. They can run parallelly, and only be trigged for go-related files.

[wu-sheng]

Your other tasks consume only < 1 m or 2-3min. Are we worth to do so?

[wu-sheng]

In the main repo, more tasks require more runnable CI slots, which could make thing worse from my experiences. If one task need over 10 mins, it worths.

[kezhenxu94]

LGTM, thanks for speeding this up!!

BTW, can't believe we're still using Go 1.13 / 1.14 🤣

[kezhenxu94]

In the main repo, more tasks require more runnable CI slots, which could make thing worse from my experiences. If one task need over 10 mins, it worths.

The tasks in this repo are faster and will release the slots faster, compared to the main repo.

Look at the results, https://github.com/apache/skywalking-cli/actions it reduces the total time from ~6m to ~3m.

I think it's OK to try this enhancement for some time and see whether the slots will be a block.

[wu-sheng]

I am not objecting, I just learn from the experience, the slot is more valuable. Anyway, if you want to do in this way, I am fine.