[C++] Acero should reject Substrait plans that require an implicit cast from decimal to float

There are a number of functions that Acero currently implements for decimal types by first casting to float implicitly. Substrait does not allow for this kind of implicit cast. If a plan does not have a decimal-native implementation of a function then it should reject the plan.

**Reporter**: [Weston Pace](https://issues.apache.org/jira/browse/ARROW-18193) / @westonpace

_{**Note**: *This issue was originally created as [ARROW-18193](https://issues.apache.org/jira/browse/ARROW-18193). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Start with Acero's Substrait plan handling and the decimal-related function implementations. Trace which functions currently rely on an implicit decimal-to-float cast, then verify that plans lacking a decimal-native implementation are rejected; the issue names no files or tests, so repository search is needed.

Written by the indexing model from the issue text.