Add infra config to ConfigurationContext

[maridematte]

Fixes https://github.com/dotnet/msbuild/issues/10123

Changes Made

Analyzers now have access to infrastructure configuration data, which contains severity and isEnabled attributes.

[JanKrivanek]

This looks great and meets original requirements.

As discussed offline - let's change CustomConfigurationData so that it has RuleId, dictionary of custom key-values, BuildAnalyzerConfiguration - that way the accessing of custome or infra config would be same (by index, or searched by RuleId)