So far, the REST config response did not include all spec constants.
The spec for `/eth/v1/config/spec` defines that the response should
include constants for all hard forks known by the beacon node. This
patch extends the corresponding response to include more constants.
* Initial commit.
* Fix path.
* Add validator keys to indices cache mechanism.
Move syncComitteeParticipants to common place.
* Fix sync participants order issue.
* Fix error code when state could not be found.
Refactor `state/validators` to use keysToIndices mechanism.
* Fix RestValidatorIndex to ValidatorIndex conversion TODOs.
* Address review comments.
* Fix REST test rules.
* REST API test framework and tests.
* Fix ValidatorIndex tests to properly handle int32, but not uint32 values.
* Fix tests to follow latest REST fixes.
* refactor restapi.sh
and add it to the test suite
* Fix issues.
Add delay timeout which is required.
* Fix restapi.sh script for Windows.
Co-authored-by: Ștefan Talpalaru <stefantalpalaru@yahoo.com>