feat(eval/method): partially port v8.1.2004

Problem:    More functions can be used as methods.
Solution:   Make various functions usable as a method.
f6ed61e148

+sound is needed for sound_* functions.

Make swapinfo and swapname take exactly one argument.
Previously, they could erroneously take one or more.

src/nvim/eval.lua

@@ -340,33 +340,33 @@ return {
     sinh={args=1, base=1, func="float_op_wrapper", data="&sinh"},
     sockconnect={args={2,3}},
     sort={args={1, 3}, base=1},
-    soundfold={args=1},
+    soundfold={args=1, base=1},
     stdioopen={args=1},
-    spellbadword={args={0, 1}},
-    spellsuggest={args={1, 3}},
+    spellbadword={args={0, 1}, base=1},
+    spellsuggest={args={1, 3}, base=1},
     split={args={1, 3}, base=1},
     sqrt={args=1, base=1, func="float_op_wrapper", data="&sqrt"},
     stdpath={args=1},
     str2float={args=1, base=1},
     str2list={args={1, 2}, base=1},
-    str2nr={args={1, 3}},
-    strcharpart={args={2, 3}},
-    strchars={args={1,2}},
-    strdisplaywidth={args={1, 2}},
-    strftime={args={1, 2}},
-    strgetchar={args={2, 2}},
-    stridx={args={2, 3}},
+    str2nr={args={1, 3}, base=1},
+    strcharpart={args={2, 3}, base=1},
+    strchars={args={1, 2}, base=1},
+    strdisplaywidth={args={1, 2}, base=1},
+    strftime={args={1, 2}, base=1},
+    strgetchar={args=2, base=1},
+    stridx={args={2, 3}, base=1},
     string={args=1, base=1},
     strlen={args=1, base=1},
-    strpart={args={2, 4}},
+    strpart={args={2, 4}, base=1},
     strptime={args=2},
-    strridx={args={2, 3}},
+    strridx={args={2, 3}, base=1},
     strtrans={args=1, base=1},
     strwidth={args=1, base=1},
-    submatch={args={1, 2}},
+    submatch={args={1, 2}, base=1},
     substitute={args=4, base=1},
-    swapinfo={args={1}},
-    swapname={args={1}},
+    swapinfo={args=1, base=1},
+    swapname={args=1, base=1},
     synID={args=3},
     synIDattr={args={2, 3}, base=1},
     synIDtrans={args=1, base=1},