[Format] Add forward compatibility checks for Decimal::bitWidth to reference libraries

[asfimport]

Parent tracking JIRA for adding forward compatibility checks for bitWidth == 128 now that ARROW-8985 is merged

Reporter: Wes McKinney / @wesm

Subtasks:

• [C++] Add forward compatibility checks for Decimal::bitWidth
• [Java] Add forward compatibility checks for Decimal::bitWidth
• [Go] Add forward compatibility checks for Decimal::bitWidth
• [Rust] Add forward compatibility checks for Decimal::bitWidth
• [C#] Add forward compatibility checks for Decimal::bitWidth
• [JS] Add forward compatibility checks for Decimal::bitWidth

_{Note: This issue was originally created as ARROW-9240. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
It doesn't seem like these will all be completed for 1.0.0.