TEIIDDES-2139 / 2237 - Adds a password token to connections and servers

* Since the url of the server is not unique, it is possible to overwrite
  passwords held in secure storage with values from other servers or
  jdbc connections.

* Adds a pass token to the servers and the connection properties which
  provides a unique reference to the password stored in secure storage

* Pass token generate with 1-way hash of the password and the url

* By carrying the pass token, each connection / server retain their unique
  password without actually holding it in the clear or revealing it until
  its actually used

* TeiidConnectionTest
 * Unit tests added for possible use cases involving password permutations
   hopefully ensuring that previous password methods of storage are taken
   into account and things stay backward compatible