Consistent code style - Githubissues

Describe the purpose of your pull request

Adds an .editorconfig file for defining a consistent code style in the repo. The code style definition is based on the coding style guidelines of the dotnet/runtime repo. Library and sample code has been completely reformatted using the new code style.

As a further step, we may consider extending our GitHub action checks to enforce that only properly formatted code can be merged into the master branch.

Note: although there is a standard setting for maximum line length in .editorconfig, the .NET tooling doesn't support it yet, so it is ignored for now.

Requirement checklist (only if applicable)

[ ] I have covered the applied changes with automated tests.
[ ] I have executed the full automated test set against my changes.
[ ] I have validated my changes against all supported platform versions.
[ ] I have read and accepted the contribution agreement.

configcat / .net-sdk

Consistent code style #59

Describe the purpose of your pull request

Requirement checklist (only if applicable)