Support custom conatiner registry

[ilaner]

Adds support for custom container registery. If a different container registry than dockerhub is configured, it will try to login and will skip the queries to dockerhub api for the python versions.

fixes: https://jira-dc.paloaltonetworks.com/browse/XSUP-33373?filter=-1

Description

[coveralls]

Pull Request Test Coverage Report for Build 8232728890

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 33 of 36 (91.67%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+11.6%) to 92.221%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
demisto_sdk/commands/common/docker_helper.py	29	32	90.63%

Files with Coverage Reduction	New Missed Lines	%
demisto_sdk/commands/common/docker_helper.py	2	96.7%

Totals
Change from base Build 78164df6-2c0e-4d10-81ab-aac078db7ce7:	11.6%
Covered Lines:	59135
Relevant Lines:	64123

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💛 - Coveralls

[yuvalbenshalom]

looks good,
see my comment and add unit test for the configuration.

[yuvalbenshalom]

Suggested change

	It is possible to provide a different container registry. In order to configure it, the following environment variables must be set:
	In order configure a custom container registry, the following environment variables must be set:

[github-actions]

Changelog(s) in markdown:

• Fixed an issue in lint and pre-commit with custom container registry #4039