Add + operation to ion jq (#196)

* Extract a filter-building method

# Conflicts:
#	src/bin/ion/commands/jq.rs

* Implement `+` and the `--slurp` option

* Fix Clippy warnings

* cargo fmt and more clean up

* Move *Math traits to their own module, document

Author: jobarr-amzn

Cargo.lock

@@ -37,6 +37,7 @@ derive_builder = "0.20.0"
 itertools = "0.13.0"
 jaq-core = "2.1.1"
 jaq-std = "2.1.0"
+bigdecimal = "0.4.8"
 
 [target.'cfg(not(target_os = "windows"))'.dependencies]
 pager = "0.16.1"