Remove the last ConfigEntry state (#1902)

* Get rid of `ConfigEntry::ExternalBIOSEnable`

- Now the BIOS files themselves are checked
- The frontend's `Config::ExternalBIOSEnable` is not affected

* Add `JITArgs`

* Pass the JIT status to the `ARM` constructors

* Encapsulate `NDS::EnableJIT`

* Pass `JITArgs` to `ARMJIT`'s constructor

* Remove the `JIT_*` `ConfigEntry`s in favor of members

- Allow all the JIT args to be set with `NDS::SetJITArgs`
- Encapsulate the JIT-related parameters in `ARMJIT` so they can reset the block cache if changed
- Update the active (or newly-created) console in the frontend with adjusted JIT args

* Make audio bit depth and interpolation configurable in `NDSArgs`

- Define enums for both
- Give those settings default values in `NDSArgs`
- Remove `ConfigEntry::AudioBitDepth`
- Initialize these settings in the relevant SPU constructors

* Move the last DSi-specific logic in `Reset` to its own subclass

* Remove `ConfigEntry::DSi_FullBIOSBoot`

- Add members to `DSi` instead for getting and setting this
- Update the frontend to accommodate these changes

* Oops, missed a spot

* Remove `ConfigEntry::Firm_MAC` and `Platform::GetConfigArray`

- Also move the MAC parsing code to `ROMManager`

* Remove the last `ConfigEntry` state

- Make GDB support configurable via members

* Add some `#ifdef`s that I'd almost forgotten

src/NDSCart.h

@@ -357,7 +357,7 @@ private:
     void Key1_Encrypt(u32* data) noexcept;
     void Key1_Decrypt(u32* data) noexcept;
     void Key1_ApplyKeycode(u32* keycode, u32 mod) noexcept;
-    void Key1_LoadKeyBuf(bool dsi, bool externalBios, u8 *bios, u32 biosLength) noexcept;
+    void Key1_LoadKeyBuf(bool dsi, u8 *bios, u32 biosLength) noexcept;
     void Key1_InitKeycode(bool dsi, u32 idcode, u32 level, u32 mod, u8 *bios, u32 biosLength) noexcept;
     void Key2_Encrypt(u8* data, u32 len) noexcept;
     void ROMEndTransfer(u32 param) noexcept;