Spurious Warning on Menu Accelerators With Mask Modifiers

### Tested versions

Reproducible in 4.3dev

### System information

N/A

### Issue description

Adding accelerators the documented way is creating spurious warnings when a modifier mask is used.
NOTE: I already checked, it's not the 2nd parameter that's the error since the 1st line here does not get an error.
```gdscript
popup.add_item("Rail Line", -1, KEY_T)
popup.add_item("Train Station", -1, KEY_MASK_CTRL | KEY_MASK_SHIFT | KEY_T)
popup.add_item("Freight Depot", -1, KEY_MASK_ALT | KEY_T)
```

The errors for the 2nd and 3rd items are:
```
W 0:00:02:0329 Integer used when an enum value is expected. If this is intended cast the integer to the enum type.
INT_AS_ENUM_WITHOUT_CAST
new_tools_container.tscn::GDScript_erqco:10
W 0:00:02:0329 Cannot pass 301989972 as Enum "Key": no enum member has matching value.
INT_AS_ENUM_WITHOUT_MATCH
new_tools_container.tscn::GDScript_erqco:10
W 0:00:02:0329 Integer used when an enum value is expected. If this is intended cast the integer to the enum type.
INT_AS_ENUM_WITHOUT_CAST
new_tools_container.tscn::GDScript_erqco:11
W 0:00:02:0329 Cannot pass 67108948 as Enum "Key": no enum member has matching value.
INT_AS_ENUM_WITHOUT_MATCH
new_tools_container.tscn::GDScript_erqco:11
```

I don't expect this since this is what the docs say to do:

### Steps to reproduce

Given above small script ^^^

### Minimal reproduction project (MRP)

N/A its in the docs

Start with the documented accelerator example and the small GDScript reproduction in the issue, then trace where modifier-mask values are checked against the Key enum. Confirm the fix by rerunning the reproduction and verifying that Ctrl+Shift+T and Alt+T produce no enum warnings while the accelerators still work.

Written by the indexing model from the issue text.