Decimal Casts are Unchecked

[tustvold]

Describe the bug

Most numeric casts, e.g. Int16 - Int8, are checked and will return an error (or null) on overflow. By contrast the decimal conversions are not. In particular:

• decimal to decimal conversion
• float to decimal conversion
• decimal to integer
• integer to decimal

To Reproduce

Expected behavior

Additional context

I believe @viirya intends to work on this, but wanted to create a ticket so it didn't get lost

[viirya]

Yea, thanks @tustvold

[alamb]

label_issue.py automatically added labels {'arrow'} from #3076

[tustvold]

Not sure if this should be reopened or a new issue created, but #3203 would suggest that truncation is not properly checked yet