file_sys: program_metadata: Add a helper function for generating reasonable default metadata.

- We need this for homebrew process initialization.

src/core/file_sys/program_metadata.cpp

@@ -51,6 +51,17 @@ Loader::ResultStatus ProgramMetadata::Load(VirtualFile file) {
     return Loader::ResultStatus::Success;
 }
 
+/*static*/ ProgramMetadata ProgramMetadata::GetDefault() {
+    ProgramMetadata result;
+
+    result.LoadManual(
+        true /*is_64_bit*/, FileSys::ProgramAddressSpaceType::Is39Bit /*address_space*/,
+        0x2c /*main_thread_prio*/, 0 /*main_thread_core*/, 0x00100000 /*main_thread_stack_size*/,
+        {}, 0xFFFFFFFFFFFFFFFF /*filesystem_permissions*/, {} /*capabilities*/);
+
+    return result;
+}
+
 void ProgramMetadata::LoadManual(bool is_64_bit, ProgramAddressSpaceType address_space,
                                  s32 main_thread_prio, u32 main_thread_core,
                                  u32 main_thread_stack_size, u64 title_id,

src/core/file_sys/program_metadata.h

@@ -44,9 +44,13 @@ public:
     ProgramMetadata();
     ~ProgramMetadata();
 
+    /// Gets a default ProgramMetadata configuration, should only be used for homebrew formats where
+    /// we do not have an NPDM file
+    static ProgramMetadata GetDefault();
+
     Loader::ResultStatus Load(VirtualFile file);
 
-    // Load from parameters instead of NPDM file, used for KIP
+    /// Load from parameters instead of NPDM file, used for KIP
     void LoadManual(bool is_64_bit, ProgramAddressSpaceType address_space, s32 main_thread_prio,
                     u32 main_thread_core, u32 main_thread_stack_size, u64 title_id,
                     u64 filesystem_permissions, KernelCapabilityDescriptors capabilities);