[server] fix name and add docstring to connection initialization functions

[server] always monkeypatch QuerierHelper to handle dates and times on SQLite The patch prevents problems due to a SQLite bug causing some values to be returned as strings instead of properly typed objects. This should probably be improved to use SQLite connection hooks. But the major improvement is that the monkeypatch is now done all the time, and not just for tests.

[testlib] put postgres test database in test/data/database directory with other (sqlite) test databases. Closes #9240765 Simplify .hgignore in passing.