Update logging to use C++ strings, try to get rid of log.h

[uweseimet]

This should be addressed after the bookworm related changes have been committed in order to avoid merge conflicts (see #1179).

The spdlog logging methods (spdlog::info, spdlog::debug etc.) accept C++ strings/string_views as arguments. This means that instead of

LOGINFO("Renamed/Moved image file '%s' to '%s'", from.c_str(), to.c_str())

just like with any other library we can just write

spdlog::info("Renamed/Moved image file '" + from + "' to '" + to + "'");

There is no need for using macros, format strings, varargs or a static buffer for log messages, and log.h most likely becomes obsolete. Note that current versions of C++ in general aim at reducing the need for using macros.

In addition, a convenience function like

string Strerrno(const string& msg) {
	return msg + ": " + string(strerror(errno));
}

shall be introduced.

[uweseimet]

@rdmark Just in case you (or somebody else, of course) can spare some time: If everything goes to plan (also see #1213) I will create a PR for #1179 and then #1182 next week. #1182 includes all changes from #1179. I have cleaned up a lot of code (except for the legacy stuff), and by making better use of C++ features (not only C++-20 but also older) rather tricky SonarQube issues have been resolved and the code volume has decreased without losing functionality. Based on my changes I could also improve the test coverage and reduce the object dependencies. There are also some minor bug fixes, which would not have justified a separate ticket.
I would welcome help with testing #1182 (not #1179, it's just an intermediate step). The respective branch is test_issue_1182. There are no known issues so far (I tested with bullseye and bookworm), but Murphy's law says that somebody else will find some ;-).

[rdmark]

@uweseimet Thanks for the heads up! This week I'm in the middle of preparing a move from Seattle to Tokyo (for work) so I won't have time for piscsi for some time, unfortunately. Once I'm settled down, maybe 2-3 months later, I'll lean back into the project and see what I can do to help.

[uweseimet]

@rdmark Seattle to Tokyo, wow! I hope everything works as planned.