Add separate worker for logging & excluded THUB_TOKEN_IS_VALID from env

[aluchianic]

Description

Fixes #784, #794

Type of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a change to the documentation

How Has This Been Tested?

• terrahub run (with/without token, with/without aws.creds)
• terrahub destroy (with/without token, with/without aws.creds)

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have checked that my changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules