test: Setup Snapshot testing library and add a snapshot test (testTextWrapperViewWillWrapText)

This change adds `https://github.com/pointfreeco/swift-snapshot-testing` as a package dependency and links it to the `damusTests` target.
It also adds one snapshot test to demonstrate its usefulness, by adding coverage to one particular aspect that we have never been able to test before: Whether or not the post text editor will wrap the text once the text gets long.

Testing of the test
-------------------

PASS

iOS: 17.0
Device: Simulator
Damus: This commit
Test steps:

1. Run `testTextWrapperViewWillWrapText`. PASS
2. Change TextViewWrapper.swift and remove this line:
```
textView.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
```
3. Rerun. It fails. PASS (This is expected)

Closes: https://github.com/damus-io/damus/issues/1562
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
Signed-off-by: William Casarin <jb55@jb55.com>

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

@@ -33,6 +33,24 @@
       "state" : {
         "revision" : "76bb7971da7fbf429de1c84f1244adf657242fee"
       }
+    },
+    {
+      "identity" : "swift-snapshot-testing",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/pointfreeco/swift-snapshot-testing",
+      "state" : {
+        "revision" : "5b356adceabff6ca027f6574aac79e9fee145d26",
+        "version" : "1.14.1"
+      }
+    },
+    {
+      "identity" : "swift-syntax",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-syntax.git",
+      "state" : {
+        "revision" : "74203046135342e4a4a627476dd6caf8b28fe11b",
+        "version" : "509.0.0"
+      }
     }
   ],
   "version" : 2