- shrink utils source file, move heartbeat and boot management into system
- improvise with 'heartbeat' functionality. include scheduler implementation that will
manage the per-module heartbeat callbacks with individual 'mode' and
'interval' settings. current ones are mqtt (including relays, lights, thermostat), debug and
influxdb. preserve heartbeat NONE, ONCE and REPEAT, REPEAT_STATUS is effectively a hbReport & status bit.
- mqtt heartbeat is managed through mqttHeartbeat() callbacks
- tweak mqtt callbacks to use lists instead of the vector, slighly reducing the size of the .bin
- update WebUI, include report setting and update hbMode values
- make sure general.h settings include new heartbeat,
move constant definitions outside of the header
- correctly include dependencies through the .cpp, avoid leaking
internal details.
- as a side-effect, base headers are no longer included recursively

- inject dummy data sequence that is expected to hold current version info
- check rtcmem markers and purge settings, since we don't want accidentally reading something as a kv
- sometimes we cannot boot b/c of certain SDK params, purge last 16KiB as well

ref. `SetOption78 1`
https://tasmota.github.io/docs/Commands/#setoptions

The original idea from Esphome:
0e59243b83/esphome/core/esphal.cpp (L275-L287)
Does not seem to be working atm. Will need to re-check with the esphome builder, c/p did not work and I tried building with gcc-10

Specific things we want to do is to have 'version' byte between 2 'marker' bytes:
217addc2bb/tasmota/settings.ino (L218-L262)       0dfa38df89/tasmota/i18n.h (L780-L782)

- general conversion from .ino modules into a separate .cpp files
- clean-up internal headers, place libraries into .h. guard .cpp with _SUPPORT flags 
- fix some instances of shared variables instead of public methods
- tweak build system to still build a single source file via os environment variable ESPURNA_BUILD_SINGLE_SOURCE

* web: optional OTA support

* add prototype

* hide under websupport

- continue #2140 , use the correct implementation for http requests not confuse code readers with our parsing
- fix data sender data duplication, run build test
- add note that this is actually really RAM heavy, some connection failures are not easily distinguishable from any code errors and are simply OOM.

also
- fix arduinoota prototype error when building without it (... ino2cpp, again)
- add comment about 160mhz into the platformio.ini

* Config: remove prototypes.h

* fixup order

* word

* add missing

* fix warning while still using .ino

* bad at c/p;

* Test: check core feature build

* order

* add missing

* webui: improve updater error message

* ota: properly check updater state and finalize on errors

* finish up ota handling refactor

* fail web upgrade when cannot find magic byte

* send updater status with no payload arg and always send payload with

* mention magic byte and flash mode in webui

* gzip magic

* make async ota at least usable. timeouts, show errors, try harder to find data after headers

* simplify setup and destruction

* cleanup class instantiations for ota and url

* handle default case of magicflashchipsize

* shorter

* blobs