[ECR] [request]: Support regular expression matching for tags in lifecycle policies

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**Tell us about your request**
What do you want us to build?
I to use regular expressions to match on tags in my lifecycle policies. For example, we have an image tagged `.dkr.ecr.us-east-1.amazonaws.com/:v1.1.0_test-4db22261f6a2ca5de2cb7eae3382dba32b3676da`.

Right now, we need to tag the image as `.dkr.ecr.us-east-1.amazonaws.com/:test-4db22261f6a2ca5de2cb7eae3382dba32b3676da_v1.1.0` so that we can use prefix matching in the lifecycle policy.

**Which service(s) is this request for?**
ECR

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We want to be able to have lifecycle policies that are more dynamic. Some things are in image tags like Git SHAs, Semver, etc. which are dynamic and we cannot match on dynamic strings in lifecycle policies.

**Are you currently working around this issue?**
For existing images, we cannot change. For new images, we can start tagging with a prefix we can filter on to be able to match in our lifecycle policies.

**Additional context**
Anything else we should know?

**Attachments**
If you think you might have additional information that you'd like to include via an attachment, please do - we'll take a look. (Remember to remove any personally-identifiable information.)

The issue names no repository files, tests, or entry points to inspect; start with the ECR lifecycle-policy request and its examples of dynamic image tags. Done would mean lifecycle policies can use regular expressions to match tags, including dynamic Git SHA or Semver portions, but the implementation scope is not defined here.

Written by the indexing model from the issue text.