Create and solve envs using mamba

[iameskild]

Changes:

• This PR will add mamba to the QHub docker images, which will speed up the image build times considerably
• To reduce the complexity of Add support for CentOS #904, I will be breaking it up into smaller PRs

Types of changes

What types of changes does your code introduce?

Put an x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features to not work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

Requires testing

• Yes
• No

In case you checked yes, did you write tests?

• Yes
• No

Further comments (optional)

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered and more.

[costrouc]

@iameskild thank you for these changes and splitting this into a PR that is easier to review 😄 . I've ran these locally as well as looked at the docker image builds on CI. Looks to build the jupyterlab image 4X faster along with many others building faster as well. Thanks!