feat(eval/method): partially port v8.1.1993

Problem:    More functions can be used as methods.
Solution:   Make various functions usable as a method.
196b466443

server2client requires +clientserver, which hasn't been ported yet.
The eval.txt docs and test_clientserver.vim tests for server2client already exist, so include those
changes.

test_bufline.vim: Test for setbufline requires v8.1.1189 (which was reverted in #10848).

src/nvim/eval.lua

@@ -291,29 +291,29 @@ return {
     rpcstart={args={1, 2}},
     rpcstop={args=1},
     rubyeval={args=1, base=1},
-    screenattr={args=2},
-    screenchar={args=2},
-    screenchars={args=2},
+    screenattr={args=2, base=1},
+    screenchar={args=2, base=1},
+    screenchars={args=2, base=1},
     screencol={},
-    screenpos={args=3},
+    screenpos={args=3, base=1},
     screenrow={},
-    screenstring={args=2},
-    search={args={1, 4}},
+    screenstring={args=2, base=1},
+    search={args={1, 4}, base=1},
     searchcount={args={0,1}},
-    searchdecl={args={1, 3}},
+    searchdecl={args={1, 3}, base=1},
     searchpair={args={3, 7}},
     searchpairpos={args={3, 7}},
-    searchpos={args={1, 4}},
+    searchpos={args={1, 4}, base=1},
     serverlist={},
     serverstart={args={0, 1}},
     serverstop={args=1},
-    setbufline={args=3},
-    setbufvar={args=3},
-    setcharsearch={args=1},
-    setcmdpos={args=1},
-    setenv={args=2},
+    setbufline={args=3, base=3},
+    setbufvar={args=3, base=3},
+    setcharsearch={args=1, base=1},
+    setcmdpos={args=1, base=1},
+    setenv={args=2, base=2},
     setfperm={args=2, base=1},
-    setline={args=2},
+    setline={args=2, base=2},
     setloclist={args={2, 4}},
     setmatches={args={1, 2}},
     setpos={args=2},