Easier caching and failure management cohesion ### State - Cleaned up the 'valueOrThrow', 'valueOrNull', 'requestValueOrThrow()', 'firstValueOrNull()' methods (#40, !31) - Callback implementation of `ProgressionReporter` (#39, !32) - Removed the Identifier interface (#41, !33) ### Spine - The endpoint 'create' returns an `Identified` type instead of a `Pair` (#30, !26) ### Deployment - Fixed a Dokka memory exaustion bug which made the documentation fail to generate (!30) - GitLab Pages now displays the documentation for the latest tag, and not for the 'main' branch (#14, !29) - Optimize GitLab CI pipeline usage (!30)