fix(plugin-ledger-connector-fabric): OpenAPI spec validation missing from plugin REST endpoints

[elenaizaguirre]

Describe the bug

Right now the constraints we define for request/response objects are not checked when a request comes in.

To Reproduce

Send an invalid request to some plugin endpoint that is invalid in a certain way and watch how it crashes the plugin resulting in internal server error vs. bad request.

Expected behavior

Fail with bad request even before the plugin's back-end code is reached if a request is sent that does not comply with the open api specs defined for that endpoint.

Logs/Stack traces

N/A

Screenshots

N/A

Cloud provider or hardware configuration:

N/A

Operating system name, version, build:

N/A

Hyperledger Cactus release version or commit (git rev-parse --short HEAD):

main

Hyperledger Cactus Plugins/Connectors Used

fabric

Additional context

The interface of the web service plugins should be extended with a getOpenApiSpecs() method that returns an OpenAPI v3 spec document (see the openapi-types package)
Then the api-server calls up this method when it's installing the web services of the plugin, obtains the open api specs and creates a validator instance from it.