fix: Defer to user-supplied input before disabling execute-api endpoint

[dgholz]

Description

Allow users to leave the default endpoint enabled when a custom domain is set.

Motivation and Context

Setting the disable_execute_api_endpoint variable to false should leave the default endpoint enabled when a custom domain is set.
This change resolves #128
This change also preserves the existing behaviour of disabling the default endpoint when a custom domain is set & no value was given for the disable_execute_api_endpoint variable.

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have used this change in my own Terraform module to see that the default endpoint was not disabled
• I have executed pre-commit run -a on my pull request

[dgholz]

I'm happy to add an example to cover this behaviour, but would appreciate some guidance on where to put it & what to include.

[github-actions]

This PR has been automatically marked as stale because it has been open 30 days
with no activity. Remove stale label or comment or this PR will be closed in 10 days

[github-actions]

This PR was automatically closed because of stale in 10 days

[github-actions]

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