Introduce appropriate defaults for standard paths

This is probably should be done before #2 to provide basic OS-specific implementation according to sandboxing and also:

• packaging requirements (lib path): https://developer.auroraos.ru/doc/software_development/guidelines/rpm_requirements
• user data expected locations: https://developer.auroraos.ru/doc/software_development/reference/user_data

First of all, this list is interesting (for the native webview demo probably):

• QStandardPaths::GenericDataLocation for /usr/share:
  • also with common: for OrgFilesLocation (/usr/share/common/$OrganizationName/)
  • could be reused with QStandardPaths::AppDataLocation: for PackageFilesLocation (/usr/share/$domain.orgName.AppName/)
    • PackageFilesLocation is also used with lib keyword (looks like not implemented for libauroraapp, just from the dev docs) (/usr/share/$domain.orgName.AppName/lib/privateLib.so)
• QStandardPaths::CacheLocation (without changes like ~/.cache/<APPNAME>, where <APPNAME> should look like domain.orgName/AppName)
• QStandardPaths::AppLocalDataLocation (or even QStandardPaths::AppConfigLocation) for ~/.local/share/domain.orgName/appName/someConfig.conf

so there're two OS-specific keywords (common and lib) and other is expected from QStandardPaths (to be patched somewhere at the qtbase/src/corelib/io/qstandardpaths*)