DMP-3534: Retention Confidence

[chrisbellingham-hmcts]

DMP-3534

Two fundamental changes in this PR:

1. The numerical values associated with retn_conf_score have been altered per the ticket requirement. See src/main/java/uk/gov/hmcts/darts/retention/enums/RetentionConfidenceScoreEnum.java
2. The retention confidence reason and score that are set on a case are now driven by the provided confidence category. A DB lookup is performed on retention_confidence_category_mapper to obtain these values. See src/main/java/uk/gov/hmcts/darts/retention/service/impl/RetentionServiceImpl.java

Some additional work has been done to facilitate these changes:

• RetentionConfidenceCategoryMapperEntity has been updated to utilise enums rather than ints, improving code readability and aligning with the approach taken for CaseRetentionEntity and CourtCaseEntity.
• The logic that performs the category lookup and that sets the confidence attributes on a court case has been centralised in RetentionServiceImpl, and calling code has been adjusted to share this common code.
• Test data classes have been created to allow for easy creation of RetentionConfidenceCategoryMapperEntity objects for both unit and integration tests going forward.
• A flyway script is included to migrate ret_conf_score values of 1 -> 0, and 2 -> 1, such that the meaning of those numerical values is consistent between DB and application.

Does this PR introduce a breaking change? (check one with "x")

[ ] Yes
[x] No