aws-lambda: Migrating from currentVersion.addAlias() to function.addAlias()

### Describe the issue

In the following commit `currentVersion.addAlias()` was deprecated: https://github.com/aws/aws-cdk/commit/a79bc47aaa6737628562c251e2f1990b2c7b88ef

The advice is to move to using `function.addAlias()`, however by moving to using that function the logical id of the alias will change, which means our alias would try to get recreated which will fail due to the alias already existing.

What is the best path to migrating off of the deprecated function?

### Links

https://github.com/aws/aws-cdk/blame/main/packages/aws-cdk-lib/aws-lambda/lib/lambda-version.ts

Start with packages/aws-cdk-lib/aws-lambda/lib/lambda-version.ts and the linked deprecation commit. Compare how currentVersion.addAlias() and function.addAlias() determine the alias logical ID, then establish a migration path that avoids recreating an existing alias. Done means the migration guidance or behavior addresses the existing-alias failure.

Written by the indexing model from the issue text.