fix(messages): inputlist() offers the mouse when it cannot be used (#41280)

Problem:
`inputlist()` advertises "click with the mouse" purely because it
implements click selection, so under the default `'mouse'` of "nvi" it
offers a click that command-line mode never receives.

Solution:
Only offer the mouse when `'mouse'` covers command-line mode, the same
condition `:help inputlist()` already documents.

test/functional/vimscript/input_spec.lua

@@ -427,6 +427,19 @@ describe('inputdialog()', function()
   end)
 end)
 
+describe('inputlist()', function()
+  it("only offers the mouse when 'mouse' applies to cmdline mode", function()
+    screen:try_resize(75, 5)
+    feed(':call inputlist(["foo", "bar"])<CR>')
+    screen:expect({ any = vim.pesc('Type number and <Enter> (q or empty cancels): ') })
+    feed('q')
+    command('set mouse=a')
+    feed(':call inputlist(["foo", "bar"])<CR>')
+    screen:expect({ any = vim.pesc('Type number and <Enter> or click with the mouse') })
+    feed('q')
+  end)
+end)
+
 describe('confirm()', function()
   it('works', function()
     api.nvim_set_option_value('more', false, {}) -- Avoid hit-enter prompt