[Feature Request] Bump NET SDK from net6 to net8

[bgavrilMS]

MSAL client type

Public, Confidential, Managed identity

Problem statement

MSAL targets net6, net6-ios and net6-android. All these SDKs are deprecated. To fix:

• add net8 support (net8, net8-android, net8-ios)
• remove net6-android and net6-ios
• optionally remove net6 after checking all tests in Id.Web and other higher level SDKs.

Proposed solution

No response

Alternatives

No response