vim test redux (#11709)

This cleans up the neovim-backed vim tests:
- removed exempted tests (we'll rely on bug reports to find missing edge
cases)
- moved all assertions into non-async fn's so that failures are
reporting on the right file/line
- removed the NeovimBackedBindingTestContext
- renamed a few things to make them clearer
- reduced the number of permutations tested in some cases to reduce
slowest test from 60s to 5s

Release Notes:

- N/A

crates/vim/test_data/test_paste.json

@@ -2,6 +2,7 @@
 {"Key":"v"}
 {"Key":"w"}
 {"Key":"y"}
+{"Get":{"state":"The quick brown\nfox ˇjumps over\nthe lazy dog","mode":"Normal"}}
 {"ReadRegister":{"name":"\"","value":"jumps o"}}
 {"Put":{"state":"The quick brown\nfox jumps oveˇr\nthe lazy dog"}}
 {"Key":"p"}
@@ -12,6 +13,7 @@
 {"Put":{"state":"The quick brown\nfox juˇmps over\nthe lazy dog"}}
 {"Key":"d"}
 {"Key":"d"}
+{"Get":{"state":"The quick brown\nthe laˇzy dog","mode":"Normal"}}
 {"ReadRegister":{"name":"\"","value":"fox jumps over\n"}}
 {"Get":{"state":"The quick brown\nthe laˇzy dog","mode":"Normal"}}
 {"Key":"p"}
@@ -23,6 +25,7 @@
 {"Key":"v"}
 {"Key":"j"}
 {"Key":"y"}
+{"Get":{"state":"The quick brown\nfox jumps ˇover\nthe lazy dog","mode":"Normal"}}
 {"ReadRegister":{"name":"\"","value":"over\nthe lazy do"}}
 {"Key":"p"}
 {"Get":{"state":"The quick brown\nfox jumps oˇover\nthe lazy dover\nthe lazy dog","mode":"Normal"}}