Add a unit test for trigger-value and do a little redesign

[github-actions[bot]]

Coverage after merging trigger-value-update into main will be

90.08%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
action.c	84.31%	50%	100%	89.47%	21–22, 25, 28, 46–47, 50, 53
builtin_triggers.c	100%	100%	100%	100%
connection.c	68.42%	33.33%	100%	76.92%	10–11, 11, 11–12, 14, 16–17, 22, 5, 7, 7
environment.c	91.94%	100%	77.78%	93.88%	40, 45–46
port.c	95.56%	75%	100%	100%	14, 23
queues.c	89.31%	73.08%	100%	96.84%	100, 17, 31, 36, 39, 39, 39–40, 54–55, 71–75, 89, 94
reaction.c	91.04%	77.27%	100%	97.56%	26–27, 37, 39, 44, 7
reactor.c	75%	50%	100%	80%	11, 16–17, 17, 17–18, 20, 28, 31–32, 32, 32–33, 35
scheduler.c	95.04%	85.71%	100%	98.89%	100–102, 69, 75–76, 84
tag.c	33.68%	26.09%	40%	40.91%	21, 23, 26–27, 27, 27, 27, 27–28, 30, 30, 30, 30, 30–31, 33, 33, 33–34, 36–37, 37, 37–38, 40, 40, 40, 40, 40–41, 43, 43, 43, 43, 43–44, 46, 56–57, 59–60, 66, 70–71, 86–88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88–90, 92
timer.c	100%	100%	100%	100%
trigger.c	93.41%	75%	100%	98.41%	10, 37, 42, 50–51, 66
trigger_value.c	100%	100%	100%	100%
src/platform
posix.c	78.08%	42.86%	90.91%	85.42%	24, 29–30, 39, 41, 41, 41–42, 44, 54–56, 64, 70, 76