Rename non-Framework project modules

Prior to this commit, the Spring Framework build would mix proper
framework modules (spring-* modules published to maven central) and
internal modules such as:
* "spring-framework-bom" (which publishes the Framework BOM with all
modules)
* "spring-core-coroutines" which is an internal modules for Kotlin
compilation only

This commit renames these modules so that they don't start with
"spring-*"; we're also moving the "kotlin-coroutines" module under
"spring-core", since it's merged in the resulting JAR.

See gh-23282

.gitignore

@@ -21,6 +21,8 @@ classes/
 /build
 buildSrc/build
 /spring-*/build
+/spring-core/kotlin-coroutines/build
+/framework-bom/build
 /integration-tests/build
 /src/asciidoc/build
 target/