Add disconnect_on_session_timeout option

[vsimon]

Describe the Feature

Expose the disconnect_on_session_timeout option which maps to this option:

https://registry.terraform.io/providers/-/aws/latest/docs/resources/ec2_client_vpn_endpoint#disconnect_on_session_timeout-1

Expected Behavior

When enabled, the "Disconnect on session timeout" option in the client VPN's AWS console is set to Enabled.

Use Case

The client VPN session is disconnected after the maximum session_timeout_hours is reached.

Describe Ideal Solution

Exposing the option in this module to enable/disable this in the underlying resource.

Alternatives Considered

No response

Additional Context

I'm happy to put up a draft PR shortly.