21.0.0 Support

Master issue/check list of stuff to do for 21.0.0 changes.

• Reverse engineer new kernel changes
• Update fusee/exosphere with new keydata/values
• Implement new changes into mesosphere
• Implement new changes into erpt
• Implement new changes into fatal
• Implement new changes into pgl
• Implement new changes into <sysmodules, create as needed>
• Update emummc
• Miscellaneous exosphere/fusee fixes for new DRAM IDs
• Make sure libnx is updated for anything relevant.

Post-release:

• Determine what other system modules need reverse engineering changes
• Reverse engineer potential new boot sysmodule changes.
• Miscellaneous post-release reverse engineering
• Miscellaneous post-release implementation work/updating