Preserve infinite step ranges in views

[jishnub]

After this, the following views are all evaluated eagerly as ranges:

julia> r = 1:4:∞
1:4:+∞

julia> view(r, 2:4)
5:4:13

julia> view(r, 2:∞)
5:4:+∞

julia> view(r, 2:2:∞)
5:8:+∞

The view forwards the arguments to getindex, which parallels the Base implementation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.99%. Comparing base (4f757e7) to head (446276d).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #203      +/-   ##
==========================================
+ Coverage   86.14%   88.99%   +2.84%     
==========================================
  Files           6       10       +4     
  Lines         758     1127     +369     
==========================================
+ Hits          653     1003     +350     
- Misses        105      124      +19     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.