`match_numbers()` returns ordered factor rather than integer

[christopherkenny]

This breaks left_join, rbind, add_reference to name a few.

library(redist)
#> Warning: package 'redist' was built under R version 4.2.1
#> Loading required package: redistmetrics
#> 
#> Attaching package: 'redist'
#> The following object is masked from 'package:stats':
#> 
#>     filter
data(iowa)
ia <- redist_map(iowa, existing_plan = cd_2010, pop_tol = 0.01)
pl <- redist_smc(ia, nsims = 100)
#> SEQUENTIAL MONTE CARLO
#> Sampling 100 99-unit maps with 4 districts and population between 753973 and 769205.
#> Split [0/3] ■ | ETA?
#> Split [3/3] ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■  | ETA 0s
pl <- match_numbers(pl, ia$cd_2010)
class(pl$district)
#> [1] "ordered" "factor"

^{Created on 2022-07-25 by the reprex package (v2.0.1)}

[CoryMcCartan]

Preferred approach to resolve: add handlers to add_reference & rbind.redist_plans. Use of left_join() is extremely rare outside 50-states (and even there we can / should just use bind_cols())