feat(af-core): contribute forms runtime schema enricher

[rismehta]

Summary

• add the Forms-side ComponentDefinitionEnricher implementation in af-core
• enrich form container definitions with runtime submit and prefill metadata
• add runtime action component definitions such as REST endpoint submit
• add focused test coverage for the Forms enricher behavior

Validation

• LC_ALL=C LANG=C mvn -pl bundles/af-core -DskipTests package

Notes

• this PR is the Forms-side implementation of the dataplane SPI-based enrichment design
• it depends on the dataplane contract and export changes on the corresponding sites-dataplane branch