Add .lfsconfig to work around SwiftPM bug (#685)

**Public-Facing Changes**
None

**Description**
Attempted workaround for https://forums.swift.org/t/swiftpm-with-git-lfs/42396/4 / swiftlang/swift-package-manager#5351.

Author: jtbandes

.lfsconfig

@@ -0,0 +1,6 @@
+[lfs]
+    # Specify the server to use when pulling Git LFS assets.
+    # This is here to work around a bug in the Swift Package Manager which prevents
+    # it from installing packages when the source repository uses Git LFS.
+    # https://forums.swift.org/t/swiftpm-with-git-lfs/42396/4
+    url = https://github.com/foxglove/mcap.git/info/lfs