Support DROP DATABASE

[linhr]

This fixes #454.

[iffyio]

can this test case also live in common.rs similar to the other drop test case?

[linhr]

Done!

[iffyio]

LGTM! cc @alamb

[alamb]

Thank you @linhr and @iffyio 🙏

[coveralls]

Pull Request Test Coverage Report for Build 11091437986

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 24 of 26 (92.31%) changed or added relevant lines in 3 files are covered.
• 761 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.04%) to 89.315%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tests/sqlparser_common.rs	21	23	91.3%

Files with Coverage Reduction	New Missed Lines	%
tests/sqlparser_common.rs	10	89.69%
src/ast/mod.rs	304	82.42%
src/parser/mod.rs	447	93.28%

Totals
Change from base Build 10980785660:	-0.04%
Covered Lines:	29807
Relevant Lines:	33373

---

💛 - Coveralls

[alamb]

🚀