all: move standalone libraries to libs/ subdirectory

The root dir of our repository has grown quite a lot the past few months.

I'd like to make it more clear where the bulk of the engine lives (`src/`) and
also make it more clear which Mach libraries are consumable as standalone projects.

As for the name of this directory, `libs` was my first choice but there's a bit of
a convention of that being external libraries in Zig projects _today_, while these
are libraries maintained as part of Mach in this repository - not external ones.

We will name this directory `libs`, and if we have a need for external libraries
we will use `external` or `deps` for that directory name. I considered other names
such as `components`, `systems`, `modules` (which are bad as they overlap with
major ECS / engine concepts), and it seems likely the official Zig package manager
will break the convention of using a `libs` dir anyway.

Performed via:

```sh
mkdir libs/
git mv freetype libs/
git mv basisu libs/
git mv gamemode libs/
git mv glfw libs/
git mv gpu libs/
git mv gpu-dawn libs/
git mv sysaudio libs/
git mv sysjs libs/
git mv ecs libs/
```

git-subtree-dir: glfw
git-subtree-mainline: 0d5b853443
git-subtree-split: 572d1144f11b353abdb64fff828b25a4f0fbb7ca

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

git mv ecs libs/

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

libs/gpu/src/sampler.zig

@@ -0,0 +1,51 @@
+const ChainedStruct = @import("types.zig").ChainedStruct;
+const FilterMode = @import("types.zig").FilterMode;
+const CompareFunction = @import("types.zig").CompareFunction;
+const Impl = @import("interface.zig").Impl;
+
+pub const Sampler = opaque {
+    pub const AddressMode = enum(u32) {
+        repeat = 0x00000000,
+        mirror_repeat = 0x00000001,
+        clamp_to_edge = 0x00000002,
+    };
+
+    pub const BindingType = enum(u32) {
+        undef = 0x00000000,
+        filtering = 0x00000001,
+        non_filtering = 0x00000002,
+        comparison = 0x00000003,
+    };
+
+    pub const BindingLayout = extern struct {
+        next_in_chain: ?*const ChainedStruct = null,
+        type: BindingType = .undef,
+    };
+
+    pub const Descriptor = extern struct {
+        next_in_chain: ?*const ChainedStruct = null,
+        label: ?[*:0]const u8 = null,
+        address_mode_u: AddressMode = .clamp_to_edge,
+        address_mode_v: AddressMode = .clamp_to_edge,
+        address_mode_w: AddressMode = .clamp_to_edge,
+        mag_filter: FilterMode = .nearest,
+        min_filter: FilterMode = .nearest,
+        mipmap_filter: FilterMode = .nearest,
+        lod_min_clamp: f32 = 0.0,
+        lod_max_clamp: f32 = 1000.0,
+        compare: CompareFunction = .undef,
+        max_anisotropy: u16 = 1,
+    };
+
+    pub inline fn setLabel(sampler: *Sampler, label: [*:0]const u8) void {
+        Impl.samplerSetLabel(sampler, label);
+    }
+
+    pub inline fn reference(sampler: *Sampler) void {
+        Impl.samplerReference(sampler);
+    }
+
+    pub inline fn release(sampler: *Sampler) void {
+        Impl.samplerRelease(sampler);
+    }
+};