Rename some FFI constructors (#5262)

Renames
* `create_from_*` -> `from_*`, e.g. `create_from_string` ->
`from_string`
* `create_*` -> `*` where the constructor doesn't take arguments, e.g.
`create_und`, -> `und`

These names were already used as named constructors, so this basically
aligns C and C++ with that.

Cargo.toml

@@ -208,10 +208,10 @@ icu_benchmark_macros = { path = "tools/benchmark/macros" }
 
 # The version here can either be a `version = ".."` spec or `git = "https://github.com/rust-diplomat/diplomat", rev = ".."`
 # Diplomat must be published preceding a new ICU4X release but may use git versions in between
-diplomat = { git = "https://github.com/rust-diplomat/diplomat", rev = "3b875c676f60a892eeb818c6a0f6f10086c69a24" }
-diplomat-runtime = { git = "https://github.com/rust-diplomat/diplomat", rev = "3b875c676f60a892eeb818c6a0f6f10086c69a24" }
-diplomat_core = { git = "https://github.com/rust-diplomat/diplomat", rev = "3b875c676f60a892eeb818c6a0f6f10086c69a24" }
-diplomat-tool = { git = "https://github.com/rust-diplomat/diplomat", rev = "3b875c676f60a892eeb818c6a0f6f10086c69a24" }
+diplomat = { git = "https://github.com/rust-diplomat/diplomat", rev = "dee60cf0463e082b89931854ed3322ce049cd31c" }
+diplomat-runtime = { git = "https://github.com/rust-diplomat/diplomat", rev = "dee60cf0463e082b89931854ed3322ce049cd31c" }
+diplomat_core = { git = "https://github.com/rust-diplomat/diplomat", rev = "dee60cf0463e082b89931854ed3322ce049cd31c" }
+diplomat-tool = { git = "https://github.com/rust-diplomat/diplomat", rev = "dee60cf0463e082b89931854ed3322ce049cd31c" }
 
 # EXTERNAL DEPENDENCIES
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