Provide a mechanism to override the configured send and receive
timeouts in the GenericMessagingTemplate.
- overload `doReceive()` to take a receive timeout argument
- for `sendAndReceive()` methods examine message headers for these
timeout values
- remove headers to avoid propagation
- avoid the unconditional rebuild of the reply message if the
original headers weren't present
- also remove headers from simple `send()` operations
- change javadocs for the setters to indicate they are now defaults
- add properties to allow the user to override the header names used
- change `TemporaryReplyChannel` to use `send` arg and change to static
- add package-protected ctor to avoid the compiler creating a
synthetic constructor for access
Issue: SPR-15591
e06c4d5116