feat: initial CLI structure

- init: create plugin boilerplate
- install: install from local path with deps
- list: show installed plugins
- validate: check manyplug.json syntax

node_modules/commander/package-support.json

@@ -0,0 +1,16 @@
+{
+  "versions": [
+    {
+      "version": "*",
+      "target": {
+        "node": "supported"
+      },
+      "response": {
+        "type": "time-permitting"
+      },
+      "backing": {
+        "npm-funding": true
+      }
+    }
+  ]
+}