Test if object is a measure tibble
Examples
# Create a measure tibble
mt <- measure:::new_measure_tbl(location = 1:5, value = rnorm(5))
is_measure_tbl(mt)
#> [1] TRUE
# Regular tibbles are not measure tibbles
is_measure_tbl(tibble::tibble(location = 1:5, value = rnorm(5)))
#> [1] FALSE