feat: enumerate GpuInfo device_type and backend fields

lua/wezterm/types/wezterm.lua

@@ -572,14 +572,31 @@ local freetype_target = {
 ---
 ---@field port string
 
+---@enum (key) GpuInfo.DeviceType
+local gpu_device_type = {
+  Other = 1,
+  IntegratedGpu = 1,
+  DiscreteGpu = 1,
+  Cpu = 1,
+}
+
+---@enum (key) GpuInfo.Backend
+local gpu_backend = {
+  Vulkan = 1,
+  Metal = 1,
+  Dx12 = 1,
+  Gl = 1,
+}
+
+---Corresponds to [`wgpu::AdapterInfo`](https://docs.rs/wgpu/latest/wgpu/struct.AdapterInfo.html)
 ---@class GpuInfo
----@field backend string
----@field device integer
----@field device_type string
----@field driver string
----@field driver_info string
 ---@field name string
 ---@field vendor integer
+---@field device integer
+---@field device_type GpuInfo.DeviceType
+---@field backend GpuInfo.Backend
+---@field driver? string
+---@field driver_info? string
 
 ---@class UnixDomain
 ---If `true`, connect to this domain on startup.