Implement minimal built-in checks for Ibis backend

[deepyaman]

This implements the built-in check machinery and a single validation (equal_to). In future PRs, I (or somebody else) can:

• Add more built-in checks
• Add more datatypes and make sure they work with the built-in checks

[codecov]

Codecov Report

Attention: Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.91%. Comparing base (ffe6c55) to head (34daca5).
Report is 1 commits behind head on ibis-dev.

Files with missing lines	Patch %	Lines
pandera/api/ibis/components.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           ibis-dev    #1885      +/-   ##
============================================
+ Coverage     92.76%   92.91%   +0.14%     
============================================
  Files           133      134       +1     
  Lines          9705     9722      +17     
============================================
+ Hits           9003     9033      +30     
+ Misses          702      689      -13     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[cosmicBboy]

thanks @deepyaman, this looks great!

Do you plan on implementing the other built-in checks in a separate PR? If so we can go ahead and merge this

[deepyaman]

thanks @deepyaman, this looks great!

Do you plan on implementing the other built-in checks in a separate PR? If so we can go ahead and merge this

Yep, will do in a separate PR!