Scan server: Enforce loop limits

[kasemir]

Fixes #3794

The scan server loop command started out as basically
for (double value=start; value<=end; value += step).
While this is quite a normal loop, with equivalent loops available in every programming language, there can be subtle rounding errors. A loop from 0 to 10.0 for example might end at 9.9999 instead of exactly 1.0, with details depending on the step size.
In PR #3305, commits 30964db and 0e2df3a tried to make it more predictable by avoiding rounding errors. Unfortunately, this disregarded the loop end points. A loop from 1.0 to '2.0' in steps of 2.0 would now yield values 1.0 and 3.0, with the latter clearly being beyond the loop end of 2.0.

A basic for (double value=1.0; value<=2.0; value += 2.0) loop would only give a value of 1.0 and then end because the next potential value of 1.0+2.0=3.0 is beyond the loop end condition.
I could argue that this original loop command behavior was good and didn't need to be "fixed" in the first place, but in keeping with the spirit of 0e2df3a to include the bounds, this update will will enforce the loop limits, resulting in a loop with values 1.0 and 2.0.

Checklist

• Testing:
  • The feature has automated tests
  • Tests were run

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[shroffk]

The computeStop seems like a reliable way to address the multitude of cases... and thank you for the unit tests.