38325 refactor flutter upgrade to be 2 part, with the second part re-entrant

cd70b Use MAP_JIT when doing an mmap for executable pages (needed for macOS Catalina).

38662 Change from using defaults to plutil for Plist parsing

2856 Update “Getting Started” path setup to support zsh shell (macOS Catalina support)

2857 Update “iOS Setup” page to reflect Xcode 11 UI update

37733 Support macOS Catalina-style signing certificate names

10010 Use simarm_x64 when targeting arm

37407 Remove multi-arch check in iOS builds

37445 Switch iOS gen_snapshot from multi-arch binary to multiple binaries

37647 Change priority of gen_snapshot search paths

iOS