Built-in configuration providers can do more robust key handling

[maryamariyan]

Found two key handling issues:

cc: @safern

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Work Items

• ConfigurationBuilder - Configuration.Json: Binding a Dictionary<string,string> error when Key contains an string url like http://www.google.es #42643 Json Configuration Provider - Handling of keys with ":"
• [Feature Request] Add a replacement for dot in EnvironmentVariablesConfigurationProvider #35989 Environment Variable Configuration Provider - Handling of keys with "."
• [API Proposal]: Allow keys with colons in config #67616

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Issue meta data

Issue content:	Found two key handling issues: ConfigurationBuilder - Configuration.Json: Binding a Dictionary<string,string> error when Key contains an string url like http://www.google.es #42643 Json Configuration Provider - Handling of keys with ":" [Feature Request] Add a replacement for dot in EnvironmentVariablesConfigurationProvider #35989 Environment Variable Configuration Provider - Handling of keys with "." cc: @safern
Issue author:	maryamariyan
Assignees:	-
Milestone:	-

[NinoFloris]

Particularly #35989 would be a wonderful fix for 6.0.

It's a major hindrance that most logging (beyond first namespace level) cannot be configured ad-hoc once a unix container has been built. (without mucking about with tools like confd or manual fix-ups inside the app)

The feature to change log levels (and other keys) via env vars is really nice and cloud native, it just falls short in polish of the last 5%.