feat: unix adaptor for elm called starmelon

Introduce starmelon, a program for executing elm functions with input
from files and writing the output back to files.

Support evaluating 4 types of values and 12 types of functions.
```elm
x : String
x : Bytes
x : VirtualDom.Node msg
x : Json.Encode.Value

f : String -> String
f : String -> Bytes
f : String -> VirtualDom.Node msg
f : String -> Json.Encode.Value
f : Bytes -> String
f : Bytes -> Bytes
f : Bytes -> VirtualDom.Node msg
f : Bytes -> Json.Encode.Value
f : Json.Encode.Value -> String
f : Json.Encode.Value -> Bytes
f : Json.Encode.Value -> VirtualDom.Node msg
f : Json.Encode.Value -> Json.Encode.Value
```

My target use case for starmelon is generating html files. It is nice
to be able to write parameterized framgents of markup in multiple
modules and then compose them into a final value. I also have in mind
attempting to replace helm (kubernetes pacakge manager) because I hate
how error prone its string based templating language is.

examples/single-page/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "single-page"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+crate-type = [ "dylib" ]
+
+[dependencies]
+