Description / Steps to reproduce / Feature proposal

For DP3, we'd like validation and coercion system implemented in the http-layer to use @loopback/types

Acceptance Criteria

• Move types folder from @loopback/repository into its own package; Make sure this PR is refined and make sure it lands [WIP] feat: add @loopback/types to be the typing system #947
• Move over the converters used in http coercion into appropriate files in @loopback/types with extensibility in mind.
  • Come up with a decorator system (@param or a new one if necessary) to introduce metadata to appropriately infer type metadata (for example Date)

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