Move core/platform/sql into modules/webdatabase

This code is specific to webdatabase. There isn't any particular reason to move
it to blink_platform.dll, which would entail removing dependencies from this
code back into the webdatabase module.

I've also renamed the folder to sqlite to indiciate that this code is specific
to sqlite. I've also removed a few unnessary mentions of the word "Chromium"
from various names.

BUG=297477
R=eseidel

Review URL: https://codereview.chromium.org/25223002

git-svn-id: svn://svn.chromium.org/blink/trunk@158670 bbb929c8-8fbe-4397-9dbb-9b2b20218538