* telnet: buffered output for async server

* telnet: make async buffer an option

* just use the queue containers directly

* try with simpler list

* exhaust buffers as much as possible in a single try

* don't forget to destroy the client object

* naming

* kill the connection earlier

* fix merge issues

* Added support for reverse telnet

* Fix issues with first command being ignored

* Fix incorrect client creation

* Integrate PR 1927

* Get rid of _telnetFirst (assumption that first line is always telnet renegotiation)

Discussed in: #1920 (comment)

- update every dynamicjsonbuffer with fixed size constructor argument
- change to ws callback registration to use a class builder (just cosmetic)
- test multiple ws data callbacks for each module
- remove some of the static strings in favour of ws data callback
- improve sensor ws callback data size, remove duplicated strings
- use static buffer in wsDebugSend
- postpone wsSend until loop, implement wsPost to allow other modules to queue message callbacks. remove Ticker based ws callbacks for data
- update WebUI files

* Telnet rewrite, no longer using ESPAsyncTCP

* Support two telnet server implementations

* Clean up diff

* Update types, no free() calls, cleanup

* Use std::unique_ptr

* Fix nullptr checks

* Fix double log with async server

* Common new connection method

* use same connected() check as sync variant

* fixup! use same connected() check as sync variant

* Fix compile issue, close connection in case of timeout and when max connections reached

* Use AyncsClient* in function call

* Allow overriding telnet port + max clients

* Do not allocate 512 bytes by default

* Use TERMINAL_BUFFER_SIZE

* Simply print timestamp for supported destinations
* Update ws destination to support 'prefix' sub-key
* Avoid void casting in telnet module

* Telnet auth depends on setting

* use same define suffix as WS_

* add to web

* no initial passwd for core