Keyspaces and Sidebar command Improvements

[rosajsx]

This pull request includes changes in the keyspace details page, keyspace table page, and sidebar command instructions.

ADDED

• New KeyspaceConnectionNotFound component to keyspaces components
• Validation on keyspace details and keyspace table detail to show a 'not found or connected message' when the connection was not selected.
• Validation on keyspace details and keyspace table detail when keyspace data are loading.
• Validation on keyspace details to show a 'not found message' when we try to access an unexisting keyspace on the current connection.
• Validation on keyspace table detail to show a 'not found message' when we try to access an unexisting table on the current keyspace.
• New contributor to contributor list on package.json

CHANGED

• Status of Data Visualization feature from wip to done