egui-wgpu: turn off the default features of wgpu (#3875)

This makes all `wgpu` features opt-in for `egui-wgpu` users.

For `eframe`, I opted to enable some `wgpu` features so users can still
use `eframe` without having to also opt-in to extra ewgpu features
(eframe is batteries-included).

Cargo.lock

@@ -1076,17 +1076,6 @@ dependencies = [
  "env_logger",
 ]
 
-[[package]]
-name = "d3d12"
-version = "0.19.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3e3d747f100290a1ca24b752186f61f6637e1deffe3bf6320de6fcb29510a307"
-dependencies = [
- "bitflags 2.4.0",
- "libloading 0.8.0",
- "winapi",
-]
-
 [[package]]
 name = "data-url"
 version = "0.3.1"
@@ -2997,12 +2986,6 @@ dependencies = [
  "getrandom",
 ]
 
-[[package]]
-name = "range-alloc"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c8a99fddc9f0ba0a85884b8d14e3592853e787d581ca1816c91349b10e4eeab"
-
 [[package]]
 name = "raw-window-handle"
 version = "0.5.2"
@@ -4277,12 +4260,10 @@ dependencies = [
  "android_system_properties",
  "arrayvec",
  "ash",
- "bit-set",
  "bitflags 2.4.0",
  "block",
  "cfg_aliases",
  "core-graphics-types",
- "d3d12",
  "glow",
  "glutin_wgl_sys",
  "gpu-alloc",
@@ -4300,7 +4281,6 @@ dependencies = [
  "once_cell",
  "parking_lot",
  "profiling",
- "range-alloc",
  "raw-window-handle 0.6.0",
  "renderdoc-sys",
  "rustc-hash",