feat: docker service improvements

[jsilva]

Describe your changes

• It adds support for using .dockerignore as an exclude filtering for tars created and sent to cloud build
  • addresses issue https://github.com/avast/wanna-ml/issues/114
• Adds the cloud build link to stdout
  • addresses feature request https://github.com/avast/wanna-ml/issues/71
• Better documents DockerService & refactors it a little

Issue ticket number and link

• https://github.com/avast/wanna-ml/issues/114
• https://github.com/avast/wanna-ml/issues/71

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] If it is a core feature, I have verified thorough tests.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 39 lines in your changes are missing coverage. Please review.

Project coverage is 74.49%. Comparing base (a85a84c) to head (8f70cbe).

Files	Patch %	Lines
src/wanna/core/services/docker.py	50.00%	28 Missing :warning:
src/wanna/core/utils/io.py	35.29%	11 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #119 +/- ## ========================================== - Coverage 74.54% 74.49% -0.06% ========================================== Files 57 58 +1 Lines 2852 2866 +14 ========================================== + Hits 2126 2135 +9 - Misses 726 731 +5 ```

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