Test additional `#BRANCHSTART p` songs to capture untested behavior

[vivaria]

The current logic works for hol6po, which has the following condition:

https://github.com/vivaria/tja2fumen/blob/a95b8e7ab1fbbd78434208b09f29a49a8055fedc/testing/data/hol6po.tja#L23

But Anzu no Uta has very strange conditions:

#BRANCHSTART p,0,0
#BRANCHSTART p,999,999

I assumed that these were supposed to be percentages from (0-100). But, what does 0% accuracy mean? And what does 999% accuracy mean? How should these conditions be written into the branchInfo fumen bytes?