qtbase Conan recipe should set build options based on settings.build_type if Qt build options are not being used

Conan package consumers should be able to consume Qt conan packages without explicitly defining qtbase specific build options (i.e. configure.bat options/features).

For example:

[settings]
os=Linux
arch=x86_64
compiler=gcc
compiler.version=9.3
compiler.libcxx=libstdc++11
build_type=RelWithDebInfo
[options]
shared=True

1. qtbase:release=True  # should not be mandatory to be set for end users
2. qtbase:separate_debug_info=True  # should not be mandatory to be set for end users
3. qtbase:force_debug_info=True  # should not be mandatory to be set for end users

The qtbase conan recipe should set Qt specific build options based on settings.build_type if Qt specific build options are not being passed for the build.