Added auto-labeling configuration to .github/mergeable.yml

[kpumuk]

I noticed mergeable is already installed as an application, so why not use it for auto-labeling? I have sketched the basic configuration, that auto-labels languages, compiler, and github actions.

See kpumuk#1 as an example

• Did you create an Apache Jira ticket? (Request account here, not required for trivial changes)
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[kpumuk]

I did not add label removal, but that is also possible, say if the MR changes to remove some files out of scope