- 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

resolve #2310

* ntp: try using sntp app from lwip, drop ntpclientlib

* fix display

* thermostat: fix day and month getters

* test build sizes with scheduler

* use system timers for once-a-minute scheduling, no polling

* tick

* avoid timestamps, use tm

* drop utc rpn operator, add utc_hour and utc_dow

* try to build with old implementation too

* dep

* notify ws

* progmem

* cleanup types

* offset tm values by 1 to match existing schedules

* avoid using ntpclientlib with rpn

* test. show debug strings in sch

* fix secureclient

* consts, fix unsyncing when changing tz (and not triggering sntp after reinit for some reason)

* startup time in seconds

* same delay as lwip

* header

* assume build timestamp is unixtime

* cache server value

* fmt

* typo

* handle dhcp request

* rename

* web

* TZ.h

* add notice about what alias means

* fix disabling NTP_SUPPORT

* scheduled ticker

* same behaviour as old module

* rollback rpn dependency check, utc_ prefixes

* ...

* comments, refactor naming