Add Cosmos db manual session token management

[JoasE]

Allows the user to retrieve session tokens from reads and writes done by a dbcontext and set session tokens to use for reads.
Adds a GetSessionTokens() extension method to DatabaseFacade which returns session tokens per container.
Adds UseSessionTokens() and AppendSessionTokens() extension methods to DatabaseFacade which allow setting and appending session tokens per container.
Adds GetSessionToken() and Use/AppendSessionToken() for the default container.
Adds option SessionTokenManagementMode to CosmosDbContextOptionsBuilder

Add 4 SessionTokenManagementMode's:

• FullyAutomatic (default) - Just the automatic token management in CosmosClient. GetSessionTokens and UseSessionTokens throw when invoked.
• SemiAutomatic - Session tokens are sent with a request if UseSessionTokens was called for that container. Otherwise automatic token management will be used
• Manual - Only tokens specified via UseSessionTokens or tracked by requests done by EF in a DbContext are used.
• EnforcedManual - Same as Manual but throws if UseSessionTokens wasn't called before a request for a specific container.

Implements: #36504

• I've read the guidelines for contributing and seen the walkthrough
• I've posted a comment on an issue with a detailed description of how I am planning to contribute and got approval from a member of the team
• The code builds and tests pass locally (also verified by our automated build checks)
• Commit messages follow this format:

        Summary of the changes
        - Detail 1
        - Detail 2

        Fixes #bugnumber

• Tests for the changes have been added (for bug fixes / features)
• Code follows the same patterns and style as existing code in this repo

[JoasE]

A few questions from me still