Console prompt should indicate uncommitted changes

[flyingsilverfin]

To improve our console UX, we can modify the transaction prompt with for example a * at the end to indicate whether the transaction has uncommitted changes.

This may end up being a state variable that is switched when a write query is performed - including define/undefine, and cleared on commit.

Note that match-insert and match-delete aren't necessarily inserting or deleting anything as the match can fail. This links with issue #166 , as we can modify this state when the user confirms they want to proceed with a insert/delete.

[flyingsilverfin]

@alexjpwalker pinged you in this because it's linked to the other issue :) this one should be relatively easy

[alexjpwalker]

Seems like we no longer show the uncommitted transaction indicator in 3.0:

> transaction blorg schema
blorg::schema> define entity person;

Success
blorg::schema> exit