Resolve differences on computation of CiBuildIndex between C# and PowerShell

[smaillet]

Fixes #24
PowerShell uses different behavior when "casting" from a double to an integer than C# does. Thus the values of the computed "CiBuildIndex" were not matching for the task and version library and scripts. This fixes the issue by making the truncation behavior explicit in the PS scripts so the output of those matches that of the C# task and library.

• Updated CiBuildInfo to use source generated Regex.
• Converted Versioning library to use DateTime instead of DateTimeOffset for conversions.
  • .NET uses a different syntax for the ISO-8601 format and that makes it impossible to compare/roundtrip test.
• Adjusted task GetBuildIndex to help make clearer intent and log same.
• Updated tests to include detailed validation of generated PS to versioning lib AND PS to generated from task to ensure all 3 agree.

[github-actions]

Test Results

29 tests  +1   29 ✅ +1   5s ⏱️ -1s
 2 suites ±0    0 💤 ±0 
 2 files   ±0    0 ❌ ±0 

Results for commit 73bf220. ± Comparison against base commit 7a40003.

This pull request removes 1 and adds 2 tests. Note that renamed tests count towards both.

Ubiquity.NET.Versioning.UT.DateTimeOffsetExtensionsTests ‑ ToBuildIndexTest

Ubiquity.NET.Versioning.UT.DateTimeExtensionsTests ‑ RoundTrippingProducesExpectedValue
Ubiquity.NET.Versioning.UT.DateTimeExtensionsTests ‑ ToBuildIndexTest

♻️ This comment has been updated with latest results.