Vendor helgoboss/helgobox (ReaLearn) as basis for custom UI fork

Stripped upstream git history; starting point for replacing the native
SWELL/Win32 mapping UI with something more suited to bulk editing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugin-reaper-realearn/dialogs/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "helgobox-dialogs"
+version = "0.1.0"
+authors = ["Benjamin Klum <benjamin.klum@helgoboss.org>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+derive_more.workspace = true
+indexmap.workspace = true
+
+[lints.clippy]
+# Enum glob use is not really dangerous in this module. Non-critical.
+enum_glob_use = "allow"