Refactor App to use the new ProjectConf module for parsing make/project.conf files.
This commit
- removes the inline ad-hoc read_value() method and its nested
helper functions, replacing them with ProjectConf's
get_str_or_none() API.
- introduces two cached helper methods (__read_project_conf() and
__get_project_conf()) to read and cache ProjectConf instances per
project.
- updates get_value() to delegate to ProjectConf and moves the
proj_dir lookup to only run in the version branch where it is
needed.
- updates the topdir init to use __read_project_conf() with a
FileNotFoundError catch for optional config files.
Signed-off-by: Jan Lindemann <jan@janware.com>