Add support for @ElementCollection in Micronaut Data JDBC

Currently, Data JDBC does not support the JPA @ElementCollection annotation. See docs: https://micronaut-projects.github.io/micronaut-data/latest/guide/#sqlAnnotations

Will be good to add support for this, given @Embeddable is already supported.

Start with the SQL annotations guide linked in the issue and inspect how existing @Embeddable support is implemented. Determine the required behavior for @ElementCollection in Data JDBC, then verify that an element collection can be mapped and persisted consistently with the supported annotation model.

Written by the indexing model from the issue text.