Provide ability to specify file to fetch password when use CONNECT command in SQL scenario [CORE6423]

[firebird-automations]

Submitted by: @pavel-zotov

It will be useful if CONNECT command will have ability to read password from local file, as it is done by ISQL when we specify '-fetch' switch.

[firebird-automations]

Modified by: @AlexPeshkoff

assignee: Alexander Peshkov [ alexpeshkoff ]