test: add a ttools helper for easier local testing

[iwpnd]

More than once I stumble upon this during testing. Previously a local test required to setup the local development environment and passing a bunch of environment variables prior to running go test ./....

docker compose up

RUN_POSTGIS_TESTS=yes \ 
RUN_REDIS_TESTS=yes \ 
PGSSLMODE=disable \ 
PGSSLKEY="" \ 
PGSSLCERT="" \ 
PGSSLROOTCERT="" \
PGHOST=localhost \
PGPORT=5432 \
PGDATABASE=tegola \
PGUSER=postgres \
PGPASSWORD=postgres \
PGUSER_NO_ACCESS=tegola_no_access \
go test  ./... -v

Now we allow for environment variables to be passed, but also default back to variables we used across tests and pipelines as default, making testing a little more comfy.

RUN_POSTGIS_TESTS=yes \ 
RUN_REDIS_TESTS=yes \ 
go test  ./... -v

wdyt?

[coveralls]

Pull Request Test Coverage Report for Build 04c4842ad-PR-861

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.0007%) to 45.489%

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Totals
Change from base Build 6387c6785:	0.0007%
Covered Lines:	5597
Relevant Lines:	12304

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💛 - Coveralls

[ARolek]

@gdey feel free to merge this.