vim-patch:8.2.0877: cannot get the search statistics

Problem:    Cannot get the search statistics.
Solution:   Add the searchcount() function. (Fujiwara Takuya, closes vim/vim#4446)
e8f5ec0d30

Additional changes:
- Tests weren't passing because the test ran assuming the cursor was at
  start of buffer but append() left the cursor at end of buffer .
  So cursor is moved to start of buffer after append.
- searchcount() added to list of builtin functions.

src/nvim/eval.lua

@@ -286,6 +286,7 @@ return {
     screenpos={args=3},
     screenrow={},
     search={args={1, 4}},
+    searchcount={args={0,1}},
     searchdecl={args={1, 3}},
     searchpair={args={3, 7}},
     searchpairpos={args={3, 7}},