add codecov for sql plugin

[penghuo]

Issue #, if available:

Description of changes:

1. add codecov support.
   2.enable xml for jacoco.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[anirudha]

Thanks

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (develop@815f4ad). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             develop     #835   +/-   ##
==========================================
  Coverage           ?   99.84%           
  Complexity         ?     2107           
==========================================
  Files              ?      207           
  Lines              ?     4657           
  Branches           ?      298           
==========================================
  Hits               ?     4650           
  Misses             ?        5           
  Partials           ?        2           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 815f4ad...7a559eb. Read the comment docs.