feat(json): convert Blobs to array of byte values

Similiar to how Vim does it, but to be consistent with how Nvim encodes
lists, add a space after every comma.

src/nvim/eval/encode.c

@@ -729,7 +729,25 @@ static inline int convert_to_json_string(garray_T *const gap,
 
 #undef TYPVAL_ENCODE_CONV_BLOB
 #define TYPVAL_ENCODE_CONV_BLOB(tv, blob, len) \
-    abort() /* TODO(seandewar) */ \
+    do { \
+      const blob_T *const blob_ = (blob); \
+      const int len_ = (len); \
+      if (len_ == 0) { \
+        ga_concat(gap, "[]"); \
+      } else { \
+        ga_append(gap, '['); \
+        char numbuf[NUMBUFLEN]; \
+        for (int i_ = 0; i_ < len_; i_++) { \
+          if (i_ > 0) { \
+            ga_concat(gap, ", "); \
+          } \
+          vim_snprintf((char *)numbuf, ARRAY_SIZE(numbuf), "%d", \
+                       (int)tv_blob_get(blob_, i_)); \
+          ga_concat(gap, numbuf); \
+        } \
+        ga_append(gap, ']'); \
+      } \
+    } while (0)
 
 #undef TYPVAL_ENCODE_CONV_FUNC_START
 #define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \