Add Fastlane config and update release workflow for v2

Single unified "Yattee" scheme replaces per-platform schemes.
Release workflow now has toggleable platform inputs instead of
matrix strategy. Standalone mac notarized workflow removed in
favor of the build_mac_notarized toggle. Share extension bundle
ID updated from Open-in-Yattee to ShareExtension.

fastlane/Matchfile

@@ -0,0 +1,3 @@
+git_url(ENV['CERTIFICATES_GIT_URL'])
+storage_mode("git")
+type("appstore")