refactor(typval)!: remove distinction of binary and nonbinary strings

This is a breaking change which will make refactor of typval and shada
code a lot easier. In particular, code that would use or check for
v:msgpack_types.binary in the wild would be broken. This appears to be
rarely used in existing plugins.

Also some cases where v:msgpack_type.string would be used to represent a
binary string of "string" type, we use a BLOB instead, which is
vimscripts native type for binary blobs, and already was used for BIN
formats when necessary.

msgpackdump(msgpackparse(data)) no longer preserves the distinction
of BIN and STR strings. This is very common behavior for
language-specific msgpack bindings. Nvim uses msgpack as a tool to
serialize its data. Nvim is not a tool to bit-perfectly manipulate
arbitrary msgpack data out in the wild.

The changed tests should indicate how behavior changes in various edge
cases.

runtime/autoload/msgpack.vim

@@ -361,7 +361,7 @@ endfunction
 let s:MSGPACK_STANDARD_TYPES = {
   \type(0): 'integer',
   \type(0.0): 'float',
-  \type(''): 'binary',
+  \type(''): 'string',
   \type([]): 'array',
   \type({}): 'map',
   \type(v:true): 'boolean',
@@ -412,9 +412,15 @@ endfunction
 ""
 " Dump |msgpack-special-dict| that represents a string. If any additional 
 " parameter is given then it dumps binary string.
-function s:msgpack_dump_string(v, ...) abort
-  let ret = [a:0 ? '"' : '="']
-  for v in a:v._VAL
+function s:msgpack_dump_string(v) abort
+  if type(a:v) == type({})
+    let val = a:v
+  else
+    let val = {'_VAL': split(a:v, "\n", 1)}
+  end
+
+  let ret = ['"']
+  for v in val._VAL
     call add(
           \ret,
           \substitute(
@@ -426,16 +432,6 @@ function s:msgpack_dump_string(v, ...) abort
   return join(ret, '')
 endfunction
 
-""
-" Dump binary string.
-function s:msgpack_dump_binary(v) abort
-  if type(a:v) == type({})
-    return s:msgpack_dump_string(a:v, 1)
-  else
-    return s:msgpack_dump_string({'_VAL': split(a:v, "\n", 1)}, 1)
-  endif
-endfunction
-
 ""
 " Dump array value.
 function s:msgpack_dump_array(v) abort
@@ -449,7 +445,7 @@ function s:msgpack_dump_map(v) abort
   let ret = ['{']
   if msgpack#special_type(a:v) is 0
     for [k, v] in items(a:v)
-      let ret += [s:msgpack_dump_string({'_VAL': split(k, "\n", 1)}),
+      let ret += [s:msgpack_dump_string({'_VAL': split(k, "\n")}),
                  \': ',
                  \msgpack#string(v),
                  \', ']
@@ -479,7 +475,7 @@ endfunction
 " Dump extension value.
 function s:msgpack_dump_ext(v) abort
   return printf('+(%i)%s', a:v._VAL[0],
-               \s:msgpack_dump_string({'_VAL': a:v._VAL[1]}, 1))
+               \s:msgpack_dump_string({'_VAL': a:v._VAL[1]}))
 endfunction
 
 ""
@@ -619,9 +615,7 @@ function msgpack#eval(s, special_objs) abort
         throw '"-invalid:Invalid string: ' . s
       endif
       call add(expr, '{''_TYPE'': v:msgpack_types.')
-      if empty(match[1])
-        call add(expr, 'binary')
-      elseif match[1] is# '='
+      if empty(match[1]) || match[1] is# '='
         call add(expr, 'string')
       else
         call add(expr, 'ext')
@@ -772,7 +766,7 @@ function msgpack#equal(a, b)
       let a = aspecial is 0 ? a:a : a:a._VAL
       let b = bspecial is 0 ? a:b : a:b._VAL
       return msgpack#equal(a, b)
-    elseif atype is# 'binary'
+    elseif atype is# 'string'
       let a = (aspecial is 0 ? split(a:a, "\n", 1) : a:a._VAL)
       let b = (bspecial is 0 ? split(a:b, "\n", 1) : a:b._VAL)
       return a ==# b
@@ -787,13 +781,17 @@ function msgpack#equal(a, b)
             " Non-special mapping cannot have non-string keys
             return 0
           endif
-          if (empty(k._VAL)
-             \|| k._VAL ==# [""]
-             \|| !empty(filter(copy(k._VAL), 'stridx(v:val, "\n") != -1')))
-            " Non-special mapping cannot have zero byte in key or an empty key
-            return 0
+          if type(k) == type({})
+            if (empty(k._VAL)
+               \|| k._VAL ==# [""]
+               \|| !empty(filter(copy(k._VAL), 'stridx(v:val, "\n") != -1')))
+              " Non-special mapping cannot have zero byte in key or an empty key
+              return 0
+            endif
+            let kstr = join(k._VAL, "\n")
+          else
+            let kstr = k
           endif
-          let kstr = join(k._VAL, "\n")
           if !has_key(akeys, kstr)
             " Protects from both missing and duplicate keys
             return 0