fix(termcap): only call callback for requested capabilities (#26546)

If multiple XTGETTCAP requests are active at once (for example, for
requesting the Ms capability and truecolor capabilities), then the
TermResponse autocommand may fire for capabilities that were not
requested. Instead, make sure that the provided callback is only called
for capabilities that were actually requested.

runtime/lua/vim/termcap.lua

@@ -39,6 +39,12 @@ function M.query(caps, cb)
       local k, rest = resp:match('^\027P1%+r(%x+)(.*)$')
       if k and rest then
         local cap = vim.text.hexdecode(k)
+        if not pending[cap] then
+          -- Received a response for a capability we didn't request. This can happen if there are
+          -- multiple concurrent XTGETTCAP requests
+          return
+        end
+
         local seq ---@type string?
         if rest:match('^=%x+$') then
           seq = vim.text