[common] Switch to boost::unordered_flat containers (#4326)

Replaces all instances of ankerl's unordered map/set with boost's
`unordered_flat_*` classes. This uses std::hash since boost::hash is
actually a lot slower.

Also adds an abstraction layer in `Common` so future changes are quicker
and easier.

Other implementation details:
- ankerl provided hash specializations for tuple and pair, so those were
  ported here
- std::erase_if doesn't work on boost, so just used the ADL'd erase_if

This should be about equal or superior performance as unordered_dense for everything except iteration.

Signed-off-by: crueter <crueter@eden-emu.dev>

- [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.

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

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4326
Reviewed-by: Lizzie and Samuel <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

src/input_common/drivers/android.h

@@ -90,7 +90,7 @@ public:
     Common::Input::ButtonNames GetUIName(const Common::ParamPackage& params) const override;
 
 private:
-    ankerl::unordered_dense::map<PadIdentifier, jobject> input_devices;
+    ::Common::unordered_map<PadIdentifier, jobject> input_devices;
 
     /// Returns the correct identifier corresponding to the player index
     PadIdentifier GetIdentifier(const std::string& guid, size_t port) const;

src/input_common/drivers/sdl_driver.cpp

@@ -732,7 +732,7 @@ SDLDriver::~SDLDriver() {
 
 std::vector<Common::ParamPackage> SDLDriver::GetInputDevices() const {
     std::vector<Common::ParamPackage> devices;
-    ankerl::unordered_dense::map<int, std::shared_ptr<SDLJoystick>> joycon_pairs;
+    ::Common::unordered_map<int, std::shared_ptr<SDLJoystick>> joycon_pairs;
     for (const auto& [key, value] : joystick_map) {
         for (const auto& joystick : value) {
             if (!joystick->GetSDLJoystick()) {

src/input_common/drivers/sdl_driver.h

@@ -9,7 +9,7 @@
 #include <atomic>
 #include <mutex>
 #include <thread>
-#include <ankerl/unordered_dense.h>
+#include "common/container/unordered_map.h"
 
 #include <SDL3/SDL.h>
 
@@ -117,7 +117,7 @@ private:
     Common::SPSCQueue<VibrationRequest> vibration_queue;
 
     /// Map of GUID of a list of corresponding virtual Joysticks
-    ankerl::unordered_dense::map<Common::UUID, std::vector<std::shared_ptr<SDLJoystick>>> joystick_map;
+    ::Common::unordered_map<Common::UUID, std::vector<std::shared_ptr<SDLJoystick>>> joystick_map;
     std::mutex joystick_map_mutex;
 
     bool start_thread = false;