Round progress percentages appropriately

[jschuurk-kr]

What & why

Solves one of the three findings in #3159:

ProgressBar percentage should be with floored instead of rounded input percentage: example Math.floor((totalFirstEntryFinished / total) * 100) : 0

Reason it should be floor is to avoid rounding a percentage >= 99.5% to 100%, suggesting a completed status. However, always using floor also means we round a percentage between 0 and 1 down to 0 in some cases where we shouldn't.

So we introduced a function (hat tip to @stacktraceghost for the conversation and the pair programming) calculateProgressPercentage() that calculates the percentage and rounds it down, except when it's within a range provided, in which case it rounds up.

There are three occurrences where we calculate a progress percentage. The function is used in two of them:

1. In ElectionProgress, which is used for the progress bars for typists, any percentage >= 0.5 and < 1 is rounded up. So when you have e.g. 600 polling stations, the 0% of progress dissappears as soon as 3 polling stations have been entered.
2. In useElectionStatus, which is used for the progress bar per status on the election status page, any percentage >=0 and < 1 is rounded up. So when you have e.g. 600 polling stations of which 599 are complete and 1 has errrors, part of the progress bar is red.

Sidenote on the MultiProgressBar: it accepts values that add up to a total larger than 100. It seems to handle that fine. Because of the data we provide it, the total will at most be slightly larger than 100.

For the third occurrence, calculateDataEntryProgress, which is used for data entry progress of a single entry when a typist submits data entry, I did not introduce the function, since it serves no purpose. It calculates the percentage completed of the pages in data entry. Since it is extremely unlikely we will ever have more than 100 pages, the issue of rounding down to 0 or up to 100 when we shouldn't, will not occur.
Since my initial solution was changing the round to a floor for all three occurrences, I have kept that change for this occurrence in this PR. At least it is consistent with floor being the default way to round in calculateProgressPercentage().

How to test

Tests were updated or added for each of the changes.

Reviewer notes

No notes.

[Lionqueen94]

Looks good!