test: add more emulator / system tests

[olavloite]

Most tests are currently using the mock server and checks whether the generated sql is as expected. The mock server however does not check the validity of the sql statements. The library should therefore include more emulator / system tests that actually do verify the statements.

[mescanne]

I've started this -- the emulator does not support NUMERIC types just yet! Working with this and I'd like at least the CREATE TABLE with all types tested in the first instance.