New node: Math (#2121)

* 2115 IP

* Initial implementation of Expression node

* Register Expression Node

* Add Expression DocumentNode Definition

* DocumentNodeImplementation::Expresssion in guess_type_from_node

* Move expression.rs to graphene-core

* WIP: Investigating 'exposed' & 'value_source' params for Expression property

* Node graph render debug IP

* Single input can change node properties; complex debug IP

* Fix epsilon in test

* Handle invalid expressions in expression_node by returning 0.0

* Run cargo fmt

* Set the default expression to "1 + 1"

* Hardcode the A and B inputs at Keavon's request

* Rename and clean up UX

* Move into ops.rs

---------

Co-authored-by: hypercube <0hypercube@gmail.com>
Co-authored-by: Keavon Chambers <keavon@keavon.com>

node-graph/gcore/Cargo.toml

@@ -78,6 +78,7 @@ web-sys = { workspace = true, optional = true, features = [
 image = { workspace = true, optional = true, default-features = false, features = [
 	"png",
 ] }
+math-parser = { path = "../../libraries/math-parser" }
 
 [dev-dependencies]
 # Workspace dependencies