Improve code-behind feature file compilation speed

[obligaron]

🤔 What's changed?

When generating a Reqnroll project with many feature files, compilation can be improved (times for BigReqnrollProject with 500 feature files) from 5.4s to 1.1s:

• original/main 5.4s
• making FixVB RegEx static 5.2s
• don't call VBFix in C# project 2.1s
• cache gherkin dialect (provider) and avoid assembly resource loads 1.2s
• avoid enum boxing 1.1s

This PR reduces compilation time by 80% (for large projects).

⚡️ What's your motivation?

Trying to improve the compilation time of Reqnroll projects.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, etc. without changing behaviour)

♻️ Anything particular you want feedback on?

I used the

📋 Checklist:

• Users should know about my change
  • I have added an entry to the "[vNext]" section of the CHANGELOG, linking to this pull request & included my GitHub handle to the release contributors list.

[gasparnagy]

Wow! Super! You are great!

Could you please add the PR number to the end of the changelog line?

[obligaron]

I added the PR number 🙂

[gasparnagy]

Thx!