feat: Implement interface persistence (#2856)

Implementing interface persistence based on a new property stored in the
interface object called `contentType`, it is used to indicate whether
the `SnapInterfaceController` should persist the interface. The property
is added at various points in our system where an interface is created.

Author: hmalik88

packages/examples/packages/browserify-plugin/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/MetaMask/snaps.git"
   },
   "source": {
-    "shasum": "D5uPpprRmrMeqwvti5+Sy5PxuCdyFlMw8PA+7OlP/WY=",
+    "shasum": "LciQX9cjRXeSErEsKRm9OEFW8jAq9doqaa9b/TfGN3Y=",
     "location": {
       "npm": {
         "filePath": "dist/bundle.js",

packages/examples/packages/browserify/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/MetaMask/snaps.git"
   },
   "source": {
-    "shasum": "87AZ5qZxOtBTdc4cRBbCRTX5vYhIlhSSJgyUc8WWi1A=",
+    "shasum": "83SohbQ4Vp/wI2lFXL6tyuvWy7bLcRSL3yZikZEZrAg=",
     "location": {
       "npm": {
         "filePath": "dist/bundle.js",

packages/snaps-controllers/coverage.json

@@ -1,6 +1,6 @@
 {
-  "branches": 92.73,
-  "functions": 96.65,
-  "lines": 97.99,
-  "statements": 97.69
+  "branches": 92.85,
+  "functions": 96.71,
+  "lines": 98,
+  "statements": 97.7
 }