Move signature before quoted text

[sosnovsky]

As described at FlowCrypt/flowcrypt-android#2963 (comment) - iOS places sender signature below quoted text, while other our apps put it above quoted text. It also breaks show quoted text toggle button:

reply from iOS app (no show quoted text button):

reply from browser extension:

So let's put sender signature above quoted text, to be consistent with other our apps and fix show quoted text toggle button.