GEODE-5977: rename --connection to --data-source

[dschneider-pivotal]

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[davebarnes97]

A few comments/questions:

• I added a 'docs' component to the JIRA ticket (GEODE-5977) because docs are affected by this change.
• For the gfsh command create jdbc-mapping, the --connection option is being deleted entirely in favor of data-source. Does this constitute a 'breaking change'?

[dschneider-pivotal]

@davebarnes97 create jdbc-mapping is experimental so it can be changed in a way that is not backwards compatible.