Rework "nancy run"

Created by: NikolayS

(#74 included to this PR)

⚠️ Some CLI options for nancy run renamed:

• --target-ddl-do → --delta-sql-do
• --target-ddl-undo → --delta-sql-undo
• --debug-timeout → --keep-alive
• --ebs-volume-size → --aws-ebs-volume-size

Code of nancy_run.sh reworked:

• bash code style,
• if [[ .. ]] everywhere
• msg, err, dbg functions for messaging
• comments for functions
• nancy run help revisited, texts for missing options added + some texts reworked