…chema (elastic#51919)

* [NP] Allow custom validations in HTTP Routes apart from @kbn/config-schema

* API docs

* Allow validate function in the route handler (run-code validation)

* Prefix RouteXXX + Params and Body Validation Aliases

* Fix test broken by lodash

* Update API docs

* Add default types for simpler manual declaration

* Add run-time validation of the RouteValidateSpec

* Expose RouteValidationError instead of SchemaTypeError

* RouteValidator as a class to match config-schema interface

* Test for not-inline handler (need to check IRouter for elastic#47047)

* Add preValidation of the input for a safer custom validation

* Better types for RouteHandlers

* [NP] Move route validation to RouteValidator wrapper

* Use the class only internally but maintain the same API

* Fix types

* Ensure RouteValidator instance in KibanaRequest.from

* Fix validator.tests (Buffer.from instead of new Buffer)

* Default precheck should allow null values

* Also allow undefined in preChecks

* MR feedback fixes

* Provide RouteValidationResolver to the validation function

* Add functional tests

* Fix new functional tests

* Fix validator additional test

* Fix test with new resolver

* Remove unused import

* Rename ValidationResolver to ValidationResultFactory and change the interface to look more like the KibanaResponseFactory

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>