Update luxon formats to correct standalone and format versions (!31)

[pomadin]

Hi, I have created simple pull request for raised issue. I don't find rules or conventions on PR format, so created it this way.

[codecov-io]

Codecov Report

Merging #37 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #37   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          10     10           
  Lines         479    479           
  Branches       46     46           
=====================================
  Hits          479    479

Impacted Files	Coverage Δ
packages/luxon/src/luxon-utils.ts	100% <100%> (ø)	⬆️

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[pomadin]

IMHO, 12/24 time formats should follow the same rules, so both are localizable formats.
Therefore they should be specified

public time12hFormat = "t";
public time24hFormat = "T";

or

public time12hFormat = "hh:mm a";
public time24hFormat = "HH:mm";

[dmtrKovalenko]

I am wondering that t and T for some locales can be super long.

[pomadin]

I doubt, the luxon implementation is restricted by Intl API, where I cannot imagine a verbose format for time, due to { hour: n, minute: d2 } etc... Do you know a locale where it could be long?