bootmanager: Log and show GL_RENDERER string when GPU is insufficient

Changes the first message to not include the OpenGL version, as the
error is caused by OpenGL failing to load.

Adds a new check for OpenGL version 4.3. This will display a message
with a similar error as well as the GL_RENDERER string. Adds a CRITICAL
log message when triggered. This prevents a crash with yuzu trying to
use older OpenGL versions.

Modifies the unsupported extension message to output the GL_RENDERER
string in the message, as well as logging the string.