Add Accessors for Day and higher

[amsingh17]

During a development project, I noticed that I was not able to run Day (or higher) on ZonedDateTime objects. The fix in this PR addresses that issue. Below is a minimum working example to show the issue

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
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   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.9.3 (2023-08-24)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> using TimeZones, Dates

julia> x = ZonedDateTime(today(), tz"UTC")
2024-09-23T00:00:00+00:00

julia> Hour(x)
0 hours

julia> Day(x)
ERROR: MethodError: no method matching Day(::ZonedDateTime)

Closest candidates are:
  (::Type{T})(::Period) where T<:Period
   @ Dates /Applications/Julia-1.9.app/Contents/Resources/julia/share/julia/stdlib/v1.9/Dates/src/periods.jl:384
  Day(::Number)
   @ Dates /Applications/Julia-1.9.app/Contents/Resources/julia/share/julia/stdlib/v1.9/Dates/src/types.jl:55
  Day(::AbstractString)
   @ Dates /Applications/Julia-1.9.app/Contents/Resources/julia/share/julia/stdlib/v1.9/Dates/src/periods.jl:21
  ...

Stacktrace:
 [1] top-level scope
   @ REPL[3]:1

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.57%. Comparing base (2bc8f50) to head (edf1e2a).
Report is 17 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #478      +/-   ##
==========================================
- Coverage   92.79%   92.57%   -0.23%     
==========================================
  Files          39       38       -1     
  Lines        1818     1831      +13     
==========================================
+ Hits         1687     1695       +8     
- Misses        131      136       +5     

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[omus]

Can you add tests?

[omus]

I originally added this accessor code when Dates.jl narrowed the types used for these sub-day accessors: 61d8299.

[amsingh17]

@omus I've added a block of tests to use the Period of a ZonedDateTime. Open to suggestions on expanding additional coverage. Thanks!

[omus]

Better to not access the internal fields

[omus]

In looking over the code again I realized that part of the original implementation was avoiding defining additional methods where they weren't required. Defining methods for year, month, etc. aren't necessary as they use TimeType so I've refactored the code to define only the necessary accessors and constructor methods. I've also expanded the test suite to ensure that changes to Dates.jl don't break accessor support here.

[omus]

Looks like I'll be dealing with LTS issues before getting this in.

Update: CI WeakDeps failure was just a fluke