0.5: Let TimeDelta::{weeks, days, hours, minutes, seconds} take i32

[pitdicker]

Making these methods fallible is not ergonomic. Especially because they are usually used with small values that comfortably fit in an i32.

This PR converts TimeDelta::{weeks, days, hours, minutes, seconds} to being infallible, and to take an i32 as argument.
They can no longer be used to create values that cover the entire range of TimeDelta. If that is needed users can use TimeDelta::new.
Also they no longer support easy round-tripping with their num_* variants that return an i64. Constructing a value is much more common that round-tripping, so it is best to make constructing ergonomic.

Because the range of TimeDelta is defined as -i64::MAX..=i64::MAX the TimeDelta::milliseconds constructor still takes an i64 as argument and remains fallible. That way a mapping between TimeDelta and a single integer remains easy.
If users want an infallible alternative, they can multiply by 1000 and use TimeDelta::microseconds.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.01%. Comparing base (d5b0e71) to head (4f79a8a).

Additional details and impacted files

@@            Coverage Diff             @@
##            0.5.x    #1515      +/-   ##
==========================================
- Coverage   94.02%   94.01%   -0.01%     
==========================================
  Files          37       37              
  Lines       16948    16833     -115     
==========================================
- Hits        15935    15826     -109     
+ Misses       1013     1007       -6     

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

[djc]

This is a great idea.

How do you feel about just ditching the try_() equivalents? People that need the extreme range can just use TimeDelta::new().

[pitdicker]

How do you feel about just ditching the try_() equivalents? People that need the extreme range can just use TimeDelta::new().

I'm all for it, we did in #1488.