Expose configuration of logger

[rcrowe]

Allow the log instance to be configured independently from other uses of the log package.

testcontainers.Logger.SetPrefix("[some-prefix] ")
testcontainers.Logger.SetOutput(io.Discard)

This is still global & it would be better to be able to pass in an instance of *log.Logger but that can be a follow-up PR. I wanted to land something small & hopefully non-contentious.

[mdelapenya]

Thanks for the contribution! I agree that having a setter/configuration option for the log would be better, so feel free to send it in a follow up PR or even saying more commits on top, whatever you prefer

[codecov]

Codecov Report

Merging #362 (cceef31) into master (a8ca295) will not change coverage.
The diff coverage is 75.00%.

@@           Coverage Diff           @@
##           master     #362   +/-   ##
=======================================
  Coverage   61.91%   61.91%           
=======================================
  Files          15       15           
  Lines        1011     1011           
=======================================
  Hits          626      626           
  Misses        288      288           
  Partials       97       97           

Impacted Files	Coverage Δ
container.go	85.29% <ø> (ø)
docker.go	64.71% <75.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a5a9803...cceef31. Read the comment docs.

[gianarb]

Great start! Thanks