Import upstream v0.16.22, stripped

Upstream commit: 474dd0229cb20cf513036619781ed97bd8073c3f
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 117 in 50 files
Dangling module declarations removed: 5
Cargo edits turning enterprise off: 14
Verification: clean
Enterprise feature gates left for rebuilt features: 19 in 18 files

Produced by tools/fork/strip.py. The full report is in docs/fork/strip-reports/ on main.

tests/resources/imap/005.txt

@@ -0,0 +1,25 @@
+From: Nathaniel Borenstein <[email protected]>
+To: Ned Freed <[email protected]>
+Date: Sun, 21 Mar 1993 23:56:48 -0800 (PST)
+Subject: Sample message
+MIME-Version: 1.0
+Content-type: multipart/mixed; boundary="simple boundary"
+
+This is the preamble.  It is to be ignored, though it
+is a handy place for composition agents to include an
+explanatory note to non-MIME conformant readers.
+
+--simple boundary
+
+This is implicitly typed plain US-ASCII text.
+It does NOT end with a linebreak.
+--simple boundary
+Content-type: text/plain; charset=us-ascii
+
+This is explicitly typed plain US-ASCII text.
+It DOES end with a linebreak.
+
+--simple boundary--
+
+This is the epilogue.  It is also to be ignored.
+