vim-patch:9.0.0449: there is no easy way to translate a key code into a string (#20168)

Problem:    There is no easy way to translate a string with a key code into a
            readable string.
Solution:   Add the keytrans() function. (closes vim/vim#11114)
cdc839353f

vim-patch:7b2d87220c6c

Add missing part of patch
7b2d87220c

src/nvim/eval.lua

@@ -236,6 +236,7 @@ return {
     json_decode={args=1, base=1},
     json_encode={args=1, base=1},
     keys={args=1, base=1},
+    keytrans={args=1, base=1},
     last_buffer_nr={},  -- obsolete
     len={args=1, base=1},
     libcall={args=3, base=3},