feat: Allow specifying environment variable to override AfterEffects executable path

What was the problem/requirement? (What/Why)

There are some scenarios where it is easier to set an environment variable to point to AfterEffects than it is to modify the path.

What was the solution? (How)

This solution implements an environment variable AFTEREFFECTS_ADAPTOR_AEFX_EXECUTABLE that allows overriding the name of the executable to run

What is the impact of this change?

Additional functionality without removing the existing functionality. Users can now override the afterfx executable path by setting the AFTEREFFECTS_ADAPTOR_AEFX_EXECUTABLE environment variable

How was this change tested?

Locally

Did you run the "Job Bundle Output Tests"? If not, why not? If so, paste the test results here.

N/A

Required: paste the contents of job_bundle_output_tests/test-job-bundle-results.txt here

Was this change documented?

Documented in DEVELOPMENT.md

Is this a breaking change?

No, it is a feature change

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

aws-deadline / deadline-cloud-for-after-effects