Add support to glimmer-wrapper for MU namespaces

resolver.resolve can accept a namespace denoted by a double colon in the first argument, for example: 
 - `service:other-namespace::i18n`
 - `template:components/other-namespace::my-component`

For example for:

```
{{ember-power-select::option}}
```

The lookup should be:

```
resolver.resolve('template:component/ember-power-select::option’)
``

And for a service example:

```
Ember.service.inject('auth-addon::main-service')
```

The lookup would be:

```
resolver.resolve('service:auth-addon::main-service’)
```

Refs: #214
Refs: emberjs/ember.js#15350 (comment)

mu-trees/addon/resolvers/glimmer-wrapper/index.js

@@ -10,6 +10,8 @@ function slasherize(dotted) {
 
 const TEMPLATE_TO_PARTIAL = /^template:(.*\/)?_([\w-]+)/;
 
+const LOOKUP_REGEX = /^([^:]+):(components\/)?([^:]+::)?([^:]+)$/;
+
 /*
  * Wrap the @glimmer/resolver in Ember's resolver API. Although
  * this code extends from the DefaultResolver, it should never
@@ -30,21 +32,18 @@ const Resolver = DefaultResolver.extend({
 
   normalize: null,
 
-  resolve(lookupString, referrer, rawString) {
-    /*
-     * Ember namespaces are part of the raw invocation passed as a third
-     * argument, for example other-addon::some-service
-     */
-    let rootName = this._configRootName;
-    let rawStringName = null;
-    if (rawString) {
-      let [namespace, name] = rawString.split('::');
-      rootName = namespace;
-      rawStringName = name;
-    }
+  resolve(lookupString, referrer) {
+    let type, name, rootName, fullMatch, componentPrefix;
 
-    let [type, lookupStringName] = lookupString.split(':');
-    let name = lookupStringName;
+    let lookupMatch = LOOKUP_REGEX.exec(lookupString);
+    if (lookupMatch) {
+      [ fullMatch, type, componentPrefix, rootName, name ] = lookupMatch;
+      rootName = (rootName && rootName.replace(/::/, '')) || this._configRootName;
+
+      if (componentPrefix) {
+        name = `${componentPrefix}${name}`;
+      }
+    }
 
     /*
      * Ember components require their lookupString to be massaged. Make this
@@ -55,16 +54,12 @@ const Resolver = DefaultResolver.extend({
       let parts = referrer.split(':src/ui/');
       referrer = `${parts[0]}:/${rootName}/${parts[1]}`;
       referrer = referrer.split('/template.hbs')[0];
-    } else if (rawString) {
+    } else if (rootName !== this._configRootName) {
       // This is only required because:
       // https://github.com/glimmerjs/glimmer-di/issues/45
       referrer = `${type}:/${rootName}/`;
     }
 
-    /* If there is no name, fallback to the name passed in the rawString */
-    if (!name) {
-      name = rawStringName;
-    }
     if (name) {
       if (type === 'service') {
         /* Services may be camelCased */
@@ -76,9 +71,8 @@ const Resolver = DefaultResolver.extend({
         /* Controllers may have.dot.paths */
         lookupString = `controller:${slasherize(name)}`;
       } else if (type === 'template') {
-        if (lookupStringName && lookupStringName.indexOf('components/') === 0) {
-          let sliced = lookupStringName.slice(11);
-          lookupString = `template:${sliced.length ? sliced : rawStringName}`;
+        if (name.indexOf('components/') === 0) {
+          lookupString = `template:${name.slice(11)}`;
         } else {
           /*
            * Ember partials are looked up as templates. Here we replace the template

mu-trees/tests/unit/resolvers/glimmer-wrapper/basic-test.js

@@ -745,7 +745,7 @@ test('Can resolve a namespaced service lookup', function(assert) {
   });
 
   assert.equal(
-    resolver.resolve('service', null, 'other-namespace::i18n'),
+    resolver.resolve('service:other-namespace::i18n'),
     service,
     'namespaced resolution resolved'
   );
@@ -771,7 +771,7 @@ test('Can resolve a namespaced component template', function(assert) {
   });
 
   assert.equal(
-    resolver.resolve('template:components/', null, 'other-namespace::my-component'),
+    resolver.resolve('template:components/other-namespace::my-component'),
     template,
     'namespaced resolution resolved'
   );