Fix Instance/Tenant Parsing for V2 Authority

[jackj-msft]

Fix Instance/Tenant Parsing for V2 Authority

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Summary of the changes (Less than 80 chars)
Fix the tenant parsing in MergedOptions for V2 authority endpoints.

Description

Currently ParseAuthorityIfNecessary assumes the authority to be formatted as {Instance}/{Tenant}.
With the introduction of v2.0 authority endpoints, this breaks the parsing of the authority.
i.e. given the authority of https://testinstance/tenant123/v2.0
The existing method will return the following:

Instance = https://testinstance/tenant123
TenantId = v2.0

What we expect is the following:

Instance = https://testinstance
TenantId = tenant123

Assumptions made:

• All authority endpoints starts with https:// (or a prefix longer than 8 characters)
• The authority is of the format {Instance}/{Tenant}/{Version} with the version being optional

[jmprieur]

LGTM
Thanks @jackj-msft

Do you have repro steps for that bug (end to end repro steps)?

[jennyf19]

@jackj-msft is there a specific version which is having the issue?

[jackj-msft]

LGTM Thanks @jackj-msft

Do you have repro steps for that bug (end to end repro steps)?

If you specify any outbound policy that uses an AppToken AND a v2 authority endpoint (either inferred by MISE or specified)
Getting the client token will fail
This is all outlined in the bug in ADO (bug 2986056)

@jackj-msft is there a specific version which is having the issue?

I've been using the latest 1.27 of the Microsoft.Identity.ServiceEssentials.AspNetCore metapackage.
The dependent Microsoft.Identity.Web package is version 2.20