### Motivation:
The datagram-related types logically mirror the TCP-based ones
(`NIOTSDatagramListenerBootstrap` vs `NIOTSListenerBootstrap`;
`NIOTSListenerChannel` vs `NIOTSDatagramListenerChannel`;
`NIOTSDatagramChannel` vs `NIOTSDatagramConnectionChannel`;
`NIOTSDatagramBootstrap` vs `NIOTSConnectionBootstrap`).
However, some of the type names could more closely resemble their TCP
counterparts to make it easier to navigate the code/understand what
their purpose is.
Additionally, the docs for some of these types are wrong, as they've
been copy-pasted into the datagram versions without changes.
### Modifications:
There are separate commits for each of the following changes:
- Fix docs for `NIOTSDatagramListenerBootstrap` and rename the file to
match the type name.
- Rename `NIOTSDatagramConnectionChannelTests` to
`NIOTSDatagramBootstrapTests` (to match `NIOTSBootstrapTests`).
- Rename `NIOTSDatagramChannel` to `NIOTSDatagramConnectionChannel` (to
match `NIOTSConnectionChannel`)
- Fix docs for `NIOTSConnectionBootstrap`.
- Rename `NIOTSDatagramBootstrap` to `NIOTSDatagramConnectionBootstrap`
(to match `NIOTSConnectionBootstrap`). This one required a deprecate and
replace since it's a public type.
### Result:
Better docs and more consistency in our type names.