ByteAether.Ulid.EntityFrameworkCore NuGet introduced

[Seramis]

Description

• Introduced ByteAether.Ulid.EntityFrameworkCore for registering Ulid type to EF Core. Supports all .NET versions from 6.0 to 10.0. Deliberately depends on the lowest version of EF Core so end-user's EF Core version would "upgrade" it to their version.
• Migrated to .slnx solution file and reorganized the content of the solution. Renamed projects, created some solution folders, etc. No effect on namespaces or end-package.
  • Introduced Directory.Build.props to bring some common properties into a single place.
  • Moved the compatibility files into a separate folder with no project. Including them as necessary into projects as a whole folder. Initially needed to use them for ByteAether.Ulid.EntityFrameworkCore as well, making them shareable, but later didn't. Decided to keep this approach.
• Updated GitHub Actions according to the new solution structure and new nuget package project.
• README.md updated to with information on ByteAether.Ulid.EntityFrameworkCore package.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Other (please specify): .sln to .slnx, CI-Debug and CI-Release build configurations introduced.

Checklist

• The PR is submitted to the correct branch (main).
• My code follows the project's coding style. (.editorconfig)
• I have commented my code, particularly in hard-to-understand areas and public interfaces.
• I have added or updated tests for the changes I made.
• All new and existing tests passed.
• I have updated the documentation where applicable.