Move parts of Rego handler input to store

[anderseknert]

When calling the handlers implemented in Rego, we provide a lot of metadata from the context:

  "regal": {
    "client": {
      "capabilities": {},
      "identifier": 1,
      "init_options": {
        "enableDebugCodelens": true,
        "evalCodelensDisplayInline": true,
        "formatter": "opa-fmt"
      }
    },
    "environment": {
      "path_separator": "/",
      "web_server_base_uri": "http://127.0.0.1:5052",
      "workspace_root_path": "/Users/foo/git/opa/regal",
      "workspace_root_uri": "file:///Users/foo/git/opa/regal"
    },
    "file": {
      "abs": "",
      "content": "",
      "lines": [],
      "name": "",
      "parse_errors": [],
      "rego_version": "unknown",
      "successful_parse_count": 0,
      "uri": ""
    }
  }

Which is often needed too. But things like the workspace root or the client init option does not change from one request to the other. So we should move this data from input and into the store and have it available somewhere under data instead.