feat(terminal)!: include cursor position in TermRequest event data (#31609)

When a plugin registers a TermRequest handler there is currently no way
for the handler to know where the terminal's cursor position was when
the sequence was received. This is often useful information, e.g. for
OSC 133 sequences which are used to annotate shell prompts.

Modify the event data for the TermRequest autocommand to be a table
instead of just a string. The "sequence" field of the table contains the
sequence string and the "cursor" field contains the cursor
position when the sequence was received.

To maintain consistency between TermRequest and TermResponse (and to
future proof the latter), TermResponse's event data is also updated to
be a table with a "sequence" field.

BREAKING CHANGE: event data for TermRequest and TermResponse is now a
table

runtime/lua/vim/_defaults.lua

@@ -515,8 +515,8 @@ do
       if channel == 0 then
         return
       end
-      local fg_request = args.data == '\027]10;?'
-      local bg_request = args.data == '\027]11;?'
+      local fg_request = args.data.sequence == '\027]10;?'
+      local bg_request = args.data.sequence == '\027]11;?'
       if fg_request or bg_request then
         -- WARN: This does not return the actual foreground/background color,
         -- but rather returns:
@@ -712,7 +712,7 @@ do
         nested = true,
         desc = "Update the value of 'background' automatically based on the terminal emulator's background color",
         callback = function(args)
-          local resp = args.data ---@type string
+          local resp = args.data.sequence ---@type string
           local r, g, b = parseosc11(resp)
           if r and g and b then
             local rr = parsecolor(r)
@@ -788,7 +788,7 @@ do
           group = group,
           nested = true,
           callback = function(args)
-            local resp = args.data ---@type string
+            local resp = args.data.sequence ---@type string
             local decrqss = resp:match('^\027P1%$r([%d;:]+)m$')
 
             if decrqss then