Expose setPeriodic (..., flexMillis) in termux-job-scheduler

[kuseni]

Expose setPeriodic (..., flexMillis) in termux-job-scheduler for more accurate job run.

setPeriodic (long intervalMillis) - Specify that this job should recur with the provided interval, not more than once per period. You have no control over when within this interval this job will be executed, only the guarantee that it will be executed at most once within this interval.

vs

setPeriodic (long intervalMillis, long flexMillis) - Specify that this job should recur with the provided interval and flex. The job can execute at any time in a window of flex length at the end of the period.