FR: Support Impala connection from CLI

[nehanene15]

The DVT supports Impala connections but it is not documented or supported via the CLI.

A user should be able to add a connection with this command:

data-validation connections add --connection-name $IMPALA_CONN Impala --host $HOST --database $DATABASE --hdfs-client $CLIENT 

We should also document this connection type, as well as an example of connecting to Hive.

[danieldeleo]

Looks like supporting Impala connection will also enable Hive as a connection

[danieldeleo]

The following packages are necessary to use impala connection type:

• pip install thrift_sasl
• pip install hdfs

[danieldeleo]

I was able to create a hive connection type using the following command:

data-validation connections add -c hive Raw --json "$(cat hive.json)"

where hive.json contains the following:

{   
  "source_type": "Impala",
  "host": "HIVE_IP_ADDRESS",
  "port": 10000,
  "database": "default",
  "auth_mechanism":"PLAIN"
}