helper/log: Add macros for target-related errors/warnings/...

helper/log: Add macros for target-related errors/warnings/...

This commit introduces macros for target related log entries
(error, warning, ...) which is a very common operation in OpenOCD:

* LOG_TARGET_ERROR
* LOG_TARGET_WARNING
* LOG_TARGET_INFO
* LOG_TARGET_DEBUG
* LOG_TARGET_DEBUG_IO

The goal is to have one macro for this common operation and to
make such log entries look the same way - to make it more readable
for humans as well easier for parsing via scripts.

Change-Id: I6166565fc9040b03d3fca5c3aa44a1ccbcf96ad2
Signed-off-by: Jan Matyas <matyas@codasip.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6667
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@sifive.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>