[PPANTT-44] feat: add get maintenance detail api (#311)

* [VAS-1171] setup new controller, service and models

* [VAS-1171] fix controller

* [VAS-1171] defined maintenance models

* [VAS-1171] added create new maintenance logic

* [VAS-1171] remove todo and updated h2 data

* [VAS-1171] added unit tests and do some improvements

* [VAS-1171] updated openapi

* [VAS-1171] fix channel tests

* [VAS-1171] format code

* [PPANTT-36] added update maintenance API

* [PPANTT-36] added javadoc

* [PPANTT-36] added unit tests

* [PPANTT-36] updated openapi

* [PPANTT-39] added list maintenance API and configured station maintenance mapper

* [PPANTT-39] updated openapi and added javadoc

* [PPANTT-39] added unit tests

* [PPANTT-44] feat: Introduced maintenance retrieval

* [PPANTT-39] fix openapi

* [PPANTT-39] fix code smell

* [PPANTT-46] added env for maintenance hours annual limit and scheduling notice

* [PPANTT-46] added get maintenance's hours summary API

* [PPANTT-46] updated openapi and added javadoc

* [PPANTT-46] added unit tests

* [PPANTT-45] added delete maintenance API and updated openapi

* [PPANTT-45] added unit tests

* [PPANTT-39] feat: Updated pom.xml

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Co-authored-by: giomella <giomella@emeal.nttdata.com>