lib/sh/util.sh: logging: separate the log_level-based indenting from the external command indenting so that the log_level-based indenting can use a different prefix. this involves propagating a new var, $log_indent, to invoked commands instead of $PS4, and always prepending $log_indent to $PS4 when printing log messages.
lib/sh/util.sh: logging: separate the log_level-based indenting from the external command indenting so that the log_level-based indenting can use a different prefix. this involves propagating a new var, $log_indent, to invoked commands instead of $PS4, and always prepending $log_indent to $PS4 when printing log messages.