Add error surfacing for git cloning errors

[Gitznik]

resolves #3167

Description

1. Use the existing dbt.exceptions.bad_package_spec() function to raise the git error and print the content to stdout.
   Decided to do this in the clone method as that is where it is done for the checkout part.
   If git returns the usage: git string with the error, I remove it from the message as it is very verbose and probably not helpful.
2. On an unknown error during cloning, the user is now advised to take a look at the debug logs for more information on the error

This handled the errors I managed to test fine:

• Invalid Repo Name
• Too many arguments as described by @tpilewicz
• Invalid revision (still works as it did before)

I did not test:

• A bad installation of git. Let me know if you know of a way to test this.

I think this works well enough for surfacing the error messages git provides, without any more contextual error handling. OSErrors should be raised as they were before.

If you think I should add unit tests for this, let me know which file/test class would be appropriate to add them. I could only find test_deps.py which did not seem to test any git functionality.

Checklist

• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the CHANGELOG.md and added information about my change

[jtcohen6]

@Gitznik Thanks for the contribution! This is a great step in the direction of more helpful error messages.

I'm going to move up the changelog entry now. Otherwise, this lgtm!

Edit: this is tricky without first rebasing/pulling changes from main. I'll plan to reorganize the changelog ahead of cutting rc1 next week.

[Gitznik]

Awesome, thank you :) Looking forward to contributing more.