core: Add missing const variants of getters for the System class

Implemented Mipmaps

time_stretch: Switch to values of Citra

video_core: Move OpenGL specific utils to its renderer

renderer_opengl: Enable alpha channel for DXT1 texture format

renderer_opengl: Correct bpp value for ASTC_2D_8X5_SRGB

Many of the Current<Thing> getters (as well as a few others) were
missing const qualified variants, which makes it a pain to retrieve
certain things from const qualified references to System.

renderer_opengl: Correct bpp value for ASTC_2D_8X5

Improved Shader accuracy on Vertex and Geometry Shaders.

Revert "Update MACOSX_DEPLOYMENT_TARGET to 10.14"

svc: Implement svcGetInfo command 0xF0000002

Update MACOSX_DEPLOYMENT_TARGET to 10.14

* remove unnecessary if-statements

* Addressed feedback

service/filesystem: Implemented DeleteDirectory & DeleteDirectoryRecursive

loader/nsp: Move secondary loader initialization to constructor

Implement sRGB support

key_manager: Use isxdigit instead of isdigit when reading key file

Crypto revisions are hex numbers and this function only checks if the string is valid for stoul in base 16, so it should be isxdigit.

configure_system: Indicate when filesystem operations fail

gl_rasterizer_cache: Fix compiler warning

Port citra-emu/citra#4367: "cubeb_sink: ignore null-name device when selecting"

gl_rasterizer: Implement primitive restart.

Implement Default Block Height for each format