[Utility] Add servicer module mock

[adshmh]

Description

Adds mock generation for the servicer module to support testing.

Issue

Part of work on #860

Type of change

Please mark the relevant option(s):

• New feature, functionality or library
• Bug fix
• Code health or cleanup
• Major breaking change
• Documentation
• Other

List of changes

• Moved servicer module mock generation to its own file.
• Updated references to the servicer module name

Testing

• make develop_test; if any code changes were made
• make test_e2e on k8s LocalNet; if any code changes were made
• e2e-devnet-test passes tests on DevNet; if any code was changed
• Docker Compose LocalNet; if any major functionality was changed or introduced
• k8s LocalNet; if any infrastructure or configuration changes were made

Required Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added, or updated, godoc format comments on touched members (see: tip.golang.org/doc/comment)
• I have tested my changes using the available tooling
• I have updated the corresponding CHANGELOG

If Applicable Checklist

• I have updated the corresponding README(s); local and/or global
• I have added tests that prove my fix is effective or that my feature works
• I have added, or updated, mermaid.js diagrams in the corresponding README(s)
• I have added, or updated, documentation and mermaid.js diagrams in shared/docs/* if I updated shared/*README(s)

[Olshansk]

@adshmh I know I wasn't added as a reviewer on this originally, but noticed it was a small PR that's been open for a few days, so I went ahead and took a look.