Numbering single measure rests

Multi-measure rests show their length by a number except for single measures. This can be changed by setting restNumberThreshold.

\version "2.24"

{
  \compressEmptyMeasures
  R1 R1*10 R1*11 \bar "||"
  \set restNumberThreshold = 0
  R1 R1*10 R1*11 \bar "||"
  \set restNumberThreshold = 10
  R1 R1*10 R1*11
}