Replace pg regress

The psqlODBC driver uses `pg_regress` to run its tests. However, `pg_regress` is closely tied to the Postgres ecosystem (and its syntax). 

Luckily, the tests are self-contained executables. This pull requests adds a `test_runner.py`, which at the moment, is a one-off Python script that runs the tests and compares the outputs just as `pg_regress` did. 

The output looks something like (note that five tests are now passing, but I do need to confirm that they are not false positives):

```
alter-test                     | FAILED (nonzero exit code)
arraybinding-test              | FAILED (nonzero exit code)
boolsaschar-test               | OK
catalogfunctions-test          | FAILED (nonzero exit code)
commands-test                  | FAILED (nonzero exit code)
connect-test                   | OK
cursors-test                   | FAILED (nonzero exit code)
cvtnulldate-test               | FAILED (nonzero exit code)
dataatexecution-test           | OK
getresult-test                 | FAILED (nonzero exit code)
insertreturning-test           | FAILED (nonzero exit code)
multistmt-test                 | OK
notice-test                    | FAILED (nonzero exit code)
params-test                    | FAILED (mismatched output)
positioned-update-test         | FAILED (nonzero exit code)
prepare-test                   | FAILED (nonzero exit code)
quotes-test                    | FAILED (nonzero exit code)
select-test                    | OK
stmthandles-test               | FAILED (nonzero exit code)
```

The other reason something can fail is `mismatched output`

`run_tests.sh` also sets up the sample tables that `pg_regress` was setting up. 

Results are also written to disk in `results/` (individual test outputs) and `results.log` (the table above)