Add pretty-printing for GuestConfig

Sample output:
```
Guest configs: {
  GuestConfig {
    target_arch: x86_64,
    device_type: phone,
    bootconfig_supported: 1,
    hctr2_supported: 1,
    android_version_number: "16",
    gfxstream_supported: 1,
    gfxstream_gl_program_binary_link_status_supported: 1,
    vhost_user_vsock: 0,
    supports_bgra_framebuffers: 0,
    prefer_drm_virgl_when_supported: 0,
    mouse_supported: 0,
    gamepad_supported: 0,
    ti50_emulator: "",
    custom_keyboard_config: (absent),
    domkey_mapping_config: (absent),
    output_audio_streams_count: 1,
    audio_settings: (absent),
    enforce_mac80211_hwsim: (absent),
    blank_data_image_mb: 0
  }
}
```

Author: Databean

base/cvd/cuttlefish/host/commands/assemble_cvd/BUILD.bazel

@@ -68,6 +68,7 @@ cf_cc_binary(
         "//cuttlefish/host/libs/config/fastboot",
         "//cuttlefish/host/libs/feature:inject",
         "//cuttlefish/posix:symlink",
+        "//cuttlefish/pretty:vector",
         "//libbase",
         "@abseil-cpp//absl/log",
         "@abseil-cpp//absl/strings",
@@ -366,6 +367,10 @@ cf_cc_library(
         "//cuttlefish/host/commands/assemble_cvd/flags:system_image_dir",
         "//cuttlefish/host/libs/config:config_utils",
         "//cuttlefish/host/libs/config:display",
+        "//cuttlefish/pretty",
+        "//cuttlefish/pretty:optional",
+        "//cuttlefish/pretty:string",
+        "//cuttlefish/pretty:struct",
         "//libbase",
         "@abseil-cpp//absl/strings",
         "@fmt",

base/cvd/cuttlefish/host/commands/assemble_cvd/assemble_cvd.cc

@@ -70,6 +70,7 @@
 #include "cuttlefish/host/libs/config/fetcher_configs.h"
 #include "cuttlefish/host/libs/feature/inject.h"
 #include "cuttlefish/posix/symlink.h"
+#include "cuttlefish/pretty/vector.h"
 
 namespace cuttlefish {
 namespace {
@@ -661,6 +662,8 @@ Result<int> AssembleCvdMain(int argc, char** argv) {
   std::vector<GuestConfig> guest_configs =
       CF_EXPECT(ReadGuestConfig(boot_image, kernel_path, system_image_dir));
 
+  VLOG(0) << "Guest configs: " << Pretty(guest_configs);
+
   VmManagerFlag vm_manager_flag =
       CF_EXPECT(VmManagerFlag::FromGlobalGflags(guest_configs));
 

base/cvd/cuttlefish/host/commands/assemble_cvd/guest_config.cc

@@ -44,6 +44,8 @@
 #include "cuttlefish/host/commands/assemble_cvd/proto/guest_config.pb.h"
 #include "cuttlefish/host/libs/config/config_utils.h"
 #include "cuttlefish/host/libs/config/display.h"
+#include "cuttlefish/pretty/optional.h"
+#include "cuttlefish/pretty/string.h"
 
 namespace cuttlefish {
 namespace {
@@ -224,6 +226,31 @@ Result<void> ParseGuestConfigTxt(const std::string& guest_config_path,
 
 }  // namespace
 
+PrettyStruct Pretty(const GuestConfig& config, PrettyAdlPlaceholder) {
+  return PrettyStruct("GuestConfig")
+      .Member("target_arch", config.target_arch)
+      .Member("device_type", config.device_type)
+      .Member("bootconfig_supported", config.bootconfig_supported)
+      .Member("hctr2_supported", config.hctr2_supported)
+      .Member("android_version_number", config.android_version_number)
+      .Member("gfxstream_supported", config.gfxstream_supported)
+      .Member("gfxstream_gl_program_binary_link_status_supported",
+              config.gfxstream_gl_program_binary_link_status_supported)
+      .Member("vhost_user_vsock", config.vhost_user_vsock)
+      .Member("supports_bgra_framebuffers", config.supports_bgra_framebuffers)
+      .Member("prefer_drm_virgl_when_supported",
+              config.prefer_drm_virgl_when_supported)
+      .Member("mouse_supported", config.mouse_supported)
+      .Member("gamepad_supported", config.gamepad_supported)
+      .Member("ti50_emulator", config.ti50_emulator)
+      .Member("custom_keyboard_config", config.custom_keyboard_config)
+      .Member("domkey_mapping_config", config.domkey_mapping_config)
+      .Member("output_audio_streams_count", config.output_audio_streams_count)
+      .Member("audio_settings", config.audio_settings)
+      .Member("enforce_mac80211_hwsim", config.enforce_mac80211_hwsim)
+      .Member("blank_data_image_mb", config.blank_data_image_mb);
+}
+
 Result<std::vector<GuestConfig>> ReadGuestConfig(
     const BootImageFlag& boot_image, const KernelPathFlag& kernel_path,
     const SystemImageDirFlag& system_image_dirs) {

base/cvd/cuttlefish/host/commands/assemble_cvd/guest_config.h

@@ -24,8 +24,9 @@
 #include "cuttlefish/host/commands/assemble_cvd/flags/boot_image.h"
 #include "cuttlefish/host/commands/assemble_cvd/flags/kernel_path.h"
 #include "cuttlefish/host/commands/assemble_cvd/flags/system_image_dir.h"
-
 #include "cuttlefish/host/commands/assemble_cvd/proto/guest_config.pb.h"
+#include "cuttlefish/pretty/pretty.h"
+#include "cuttlefish/pretty/struct.h"
 
 namespace cuttlefish {
 
@@ -51,6 +52,9 @@ struct GuestConfig {
   int blank_data_image_mb = 0;
 };
 
+PrettyStruct Pretty(const GuestConfig&,
+                    PrettyAdlPlaceholder unused = PrettyAdlPlaceholder());
+
 Result<std::vector<GuestConfig>> ReadGuestConfig(
     const BootImageFlag&, const KernelPathFlag& kernel_path,
     const SystemImageDirFlag& system_image_dir);