[core, hle, video_core, memory] Improve multi-process, display layers, dynamic shader cache and rework overlay (#4238)

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------

- Dynamic shader cache reloading capability for qlaunch
- Multi-process improvements (thanks to @frank1734), instead of just using the main application we now respect caller process (also did it for HID devices while I was at it)
- Layer stack masks & shared buffer screenshot for video core, added different masks (screenshot, recording, etc.) this was discovered as an issue due to how in qlaunch the transition was not right between applications. May not be perfect but also fixes screenshots while using qlaunch
- Reworked overlay display management (input and visibility) - instead of random numbers as I've previously did, I decided to add an AppletZIndex enum for better readability. Also split capability of input by touch and gamepad.
- etc.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4238
Reviewed-by: Samuel <lizzie@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

src/core/hle/kernel/kernel.cpp

@@ -349,9 +349,18 @@ struct KernelCore::Impl {
         object_name_global_data.emplace(kernel);
     }
 
-    void MakeApplicationProcess(KernelCore& kernel, KProcess* process) {
+    void SetApplicationProcess(KernelCore& kernel, KProcess* process) {
+        if (application_process == process)
+            return;
+
+        KProcess* const previous = application_process;
         application_process = process;
-        application_process->Open(kernel);
+
+        if (application_process != nullptr)
+            application_process->Open(kernel);
+
+        if (previous != nullptr)
+            previous->Close(kernel);
     }
 
     /// Sets the host thread ID for the caller.
@@ -879,8 +888,8 @@ void KernelCore::RemoveProcess(KProcess* process) {
     }
 }
 
-void KernelCore::MakeApplicationProcess(KProcess* process) {
-    impl->MakeApplicationProcess(*this, process);
+void KernelCore::SetApplicationProcess(KProcess* process) {
+    impl->SetApplicationProcess(*this, process);
 }
 
 KProcess* KernelCore::ApplicationProcess() {
@@ -891,6 +900,14 @@ const KProcess* KernelCore::ApplicationProcess() const {
     return impl->application_process;
 }
 
+KScopedAutoObject<KProcess> KernelCore::GetProcessByProcessId(u64 process_id) {
+    std::scoped_lock lk{impl->process_list_lock};
+    for (auto* const process : impl->process_list)
+        if (process != nullptr && process->GetProcessId() == process_id)
+            return {*this, process};
+    return {*this, nullptr};
+}
+
 std::list<KScopedAutoObject<KProcess>> KernelCore::GetProcessList() {
     std::list<KScopedAutoObject<KProcess>> processes;
     std::scoped_lock lk{impl->process_list_lock};

src/core/hle/kernel/kernel.h

@@ -124,8 +124,8 @@ public:
     void AppendNewProcess(KProcess* process);
     void RemoveProcess(KProcess* process);
 
-    /// Makes the given process the new application process.
-    void MakeApplicationProcess(KProcess* process);
+    /// Makes the given process the current application process.
+    void SetApplicationProcess(KProcess* process);
 
     /// Retrieves a pointer to the application process.
     KProcess* ApplicationProcess();
@@ -133,6 +133,9 @@ public:
     /// Retrieves a const pointer to the application process.
     const KProcess* ApplicationProcess() const;
 
+    /// Retrieves the process with the given process ID, or a null object.
+    KScopedAutoObject<KProcess> GetProcessByProcessId(u64 process_id);
+
     /// Retrieves the list of processes.
     std::list<KScopedAutoObject<KProcess>> GetProcessList();