feat: Extend diagnostic information's

[buhtz]

Extend diagnostic information's

1. Python executable path.
2. Rsync environment variables.
3. Modified username replacement to replace users homepath and not only its username.
4. PEP8 etc

About 1: Related to #1316 where the path to systems python interpreter was "hacked" via "pyenv". This info will catch situations like that.

About 2: Related to #1247. Rsync 3.2.4 do use a different way of argument protection. The situation is complex and the environment variables RSYNC_OLD_ARGS and RSYNC_PROTECT_ARGS to influence that.

About 3: The replacement is done on the whole JSON-like string and not on specific elements. To prevent replacement of technical informations (e.g. about "rsync") when a user do use a technical login name (e.g. "rsync") now we search for the users homepath and not only is username.

About 4: Replaced use of os.path with high-level API pathlib.Path. Also reduced "cyclomatic complexity" (was 15) of get_diagnostics() with moving one code part into its own private method.

The output no looks like this

    "backintime": {
        "name": "Back In Time",
        "version": "1.3.2",
        "latest-config-version": 6,
        "local-config-file": "/home/UsernameReplaced/.config/backintime/config",
        "local-config-file-found": true,
        "global-config-file": "/etc/backintime/config",
        "global-config-file-found": false,
        "distribution-package": "/home/UsernameReplaced/ownCloud/my.work/bit/backintime",
        "started-from": "/home/UsernameReplaced/ownCloud/my.work/bit/backintime/common",
        "running-as-root": false,
        "user-callback": "/home/UsernameReplaced/.config/backintime/user-callback",
        "git-branch": "improve_diagnostics",
        "git-hash": "eb59d0aedf9b383a0fef646928490701641aeaa8"
    },
    "host-setup": {
        "platform": "Linux-5.10.0-18-amd64-x86_64-with-glibc2.31",
        "system": "Linux #1 SMP Debian 5.10.140-1 (2022-09-02)",
        "os-release": "Debian GNU/Linux 11 (bullseye)",
        "display-system": "tty",
        "locale": "de_DE, UTF-8",
        "PATH": "/home/UsernameReplaced/.local/bin:/home/UsernameReplaced/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games",
        "RSYNC_OLD_ARGS": "(not set)",
        "RSYNC_PROTECT_ARGS": "(not set)"
    },
    "python-setup": {
        "python": "3.9.2 default Feb 28 2021 17:03:44 CPython GCC 10.2.1 20210110",
        "python-executable": "/usr/bin/python3",
        "python-executable-symlink": true,
        "python-executable-resolved": "/usr/bin/python3.9",
        "sys.path": [
            "/home/UsernameReplaced/ownCloud/my.work/bit/backintime/qt/plugins",
            "/home/UsernameReplaced/ownCloud/my.work/bit/backintime/common/plugins",
            "/home/UsernameReplaced/ownCloud/my.work/bit/backintime/plugins",
            "/home/UsernameReplaced/ownCloud/my.work/bit/backintime/common",
            "/usr/lib/python39.zip",
            "/usr/lib/python3.9",
            "/usr/lib/python3.9/lib-dynload",
            "/usr/local/lib/python3.9/dist-packages",
            "/usr/lib/python3/dist-packages",
            "/usr/lib/python3.9/dist-packages"
        ],
        "qt": "PyQt 5.15.2 / Qt 5.15.2"
    },
    "external-programs": {
        "rsync": "3.2.3",
        "ssh": "OpenSSH_8.4p1 Debian-5+deb11u1, OpenSSL 1.1.1n  15 Mar 2022",
        "sshfs": "3.7.1",
        "encfs": "1.9.5",
        "shell": "/bin/bash",
        "shell-version": "GNU bash, Version 5.1.4(1)-release (x86_64-pc-linux-gnu)"
    }
}

[aryoda]

Thanks for implementing it tout de suite!

This way we can see now if the distro python was bypassed...