Tweaks discovered when using Compound overrides. (#4456)

- Fixes a bug where gradients wouldn't use the latest tokens after first use.
- Makes the bloom aware of colour overrides (and discovers a bug with dark mode).
- Decouples HomeScreenCell from the HomeScreenViewModel.Context (so it can be previewed with colour overrides).

ElementX.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -15,7 +15,7 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/element-hq/compound-ios",
       "state" : {
-        "revision" : "8d7ca2e413026735b724044847ff1ae3b40563f0"
+        "revision" : "4ad0bd0acd825a905bb4955b32979fe34cc538eb"
       }
     },
     {
@@ -275,8 +275,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/pointfreeco/swift-snapshot-testing",
       "state" : {
-        "revision" : "37230a37e83f1b7023be08e1b1a2603fcb1567fb",
-        "version" : "1.18.4"
+        "revision" : "1be8144023c367c5de701a6313ed29a3a10bf59b",
+        "version" : "1.18.3"
       }
     },
     {