[common] merge RenderBackend and ShaderBackend options (#3313)

first of all it makes UI a tad bit more simple and benefits the end user
second, it allows to add new backends a bit more easily
and also, there was a shader backend option in android... we don't use opengl in android
so may as well save ourselves the trouble, aye

![image](/attachments/c0195bca-da18-4907-9e4a-3b62c4292f1a)

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

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3313
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Reviewed-by: DraVee <dravee@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/android/app/src/main/res/values-pl/strings.xml

@@ -88,9 +88,6 @@
     <string name="debug_knobs_description">Wyłącznie do użytku deweloperskiego.</string>
     <string name="debug_knobs_hint">0 do 65535</string>
 
-    <!-- Shader Backend -->
-    <string name="shader_backend_glsl">GLSL</string>
-    <string name="shader_backend_glasm">GLASM</string>
     <!-- NVDEC Emulation -->
     <string name="nvdec_emulation">Emulacja NVDEC</string>
     <string name="nvdec_emulation_description">Wybierz metodę dekodowania wideo (NVDEC).</string>
@@ -437,8 +434,6 @@
     <!-- Graphics settings strings -->
     <string name="renderer_resolution">Rozdzielczość (Handheld/Zadokowany)</string>
     <string name="renderer_vsync">Synchronizacja pionowa VSync</string>
-    <string name="shader_backend">Backend shaderów</string>
-    <string name="shader_backend_description">Wybierz metodę kompilacji shaderów.</string>
     <string name="renderer_scaling_filter">Filtr adaptacji rozdzielczości</string>
     <string name="fsr_sharpness">Ostrość FSR</string>
     <string name="fsr_sharpness_description">Kontroluje ostrość obrazu w FSR.</string>