HTTP-API: `exists` endpoint should return metadata

[gramian]

ArcadeDB Version: 23.2.1 (build e8f512f/1677638572021/main)

JDK Version: openjdk 11.0.18 2023-01-17

OS: MacOS 12.6

As for the other non-server-command endpoints, the /api/v1/exists/ endpoint should also return user and version info in addition to the result.

Expected behavior

{"user":"root","version":"23.2.1 (build e8f512fa466c4a32ef9d14d89af20e7ac2859c7e/1677638572021/main)","result":true}

Actual behavior

{ "result" : true}

Steps to reproduce

curl -X GET http://localhost:2480/api/v1/exists/test --user root:mypassword

[lvca]

Implemented.

[gramian]

Tested and works.