scripts/resulttool: allow to replace test raw status with custom string

scripts/resulttool: allow to replace test raw status with custom string

Add a STATUS_STRINGS dictionnary matching raw statuses to custom strings.
Whenever a regression must be reported, raw status is searched in the
custom statuses dict (key search is case insensitive). If no custom string
is found, raw status is kept and used in regression report

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>