Add shutdown hook to close AsyncHttpClient.

[pujagani]

Add Threadfactory to AsyncHttpClient to update threadfactory to use daemon threads.

Description

The changes are related to issue #8159.

Motivation and Context

The AsyncHttpClient uses non-daemon long-running threads. When the program finishes, these threads prevent the JVM from shutting down. Hence, the AsyncHttpClient was not closed. Thus, the application cannot exit.
The changes make the AsyncHttpClient threads as daemon threads. So now the JVM can exit and initiate shutdown. Additionally, the changes add a shutdown hook to close the client.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[diemol]

Thank you, @pujagani!