Add relaxed binding support to `ChangeSpringPropertyKey`

What problem are you trying to solve?

Trying to migrate Spring properties set via relaxed binding environment variables during a Spring Boot upgrade migration.

Describe the solution you'd like

ChangeSpringPropertyValue seems to support finding the items via relaxed bindings: https://github.com/openrewrite/rewrite-spring/blob/196dc5f133b61eb56f8ab1c3150fffe68d6f2fd6/src/main/java/org/openrewrite/java/spring/ChangeSpringPropertyValue.java#L69
I'd like to see this support in ChangeSpringPropertyKey as well (which seems to be absent atm).

For example, in the Spring Boot 2.3 upgrade if I have an application.properties containing server.use-forward-headers=true it will currently migrate to server.forward-headers-strategy=true.

However, if I have the environment variable equivalent, SERVER_USEFORWARDHEADERS=true, in a .env file, docker-compose.yml, etc it will not currently be migrated to SERVER_FORWARDHEADERSTRATEGY=true

Start with ChangeSpringPropertyKey and compare its lookup behavior with ChangeSpringPropertyValue.java, especially the relaxed-binding support referenced in the issue. Verify the behavior against the application.properties example and equivalent SERVER_USEFORWARDHEADERS values in .env or docker-compose.yml; done means the environment-variable form migrates to SERVER_FORWARDHEADERSTRATEGY.