Update Process Model Search to Allow Relative Imports

[kds300]

Issue Number: #902

Objective of pull request: Modify process model search process to allow for relative imports when defining custom processes and process models.

Pull request checklist

Your PR fulfills the following requirements:

• Issue created that explains the change and why it's needed
• Tests are part of the PR (for bug fixes / features)
• Docs reviewed and added / updated if needed (for bug fixes / features)
• PR conforms to Coding Conventions
• PR applys BSD 3-clause or LGPL2.1+ Licenses to all code files
• Lint (flakeheaven lint src/lava tests/) and (bandit -r src/lava/.) pass locally
  • Changed code does not raise issues.
• Build tests (pytest) passes locally

Pull request type

Please check your PR type:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation changes
• Other (please describe):

What is the current behavior?

• Relative imports break process model search.

What is the new behavior?

• Relative imports can now be used in defining process models.

Does this introduce a breaking change?

• Yes
• No