[WebPubSub] Update send methods signatures

[xingsy97]

Description

Diff with latest version (a beta version, 1.1.0b1)

1. Add three override signatures for send* methods, application/json, text/plain, and application/octet-stream.
2. Add union type to parameter content for send* methods
3. Add groups parameter to get_client_access_token

Note: the next two items were already included in latest version 1.1.0b1, but will be shown in the diff with stable version 1.0.1

4. Add new parameter filter for send* methods
5. Add new methods remove_connection_from_all_groups

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

azure-messaging-webpubsubservice

[xingsy97]

Hi @msyyc , architect told me new API view is ok for him to approve. Please help merge this request.