allow to use api helpers to execute something when button event happens

fix #2592 (for real this time)

cannot declare constexpr objects like that with old compiler
fix #2594

ref. #2585 and 3be53055

fix #2592

re-apply fix from #2181
resolve #2586

minimal & single-source builds should coexist yet again

also fixing leftover API dependency issues

sdk would silently cancel both

helper would block 2nd action, wifi is not enabled yet
fixing behaviour introduced in 28f3b7da8

also make boot action optional

also get rid of flashstringhelper

*should* fix most constexpr'ness issues when inlining
(but, now has a small overhead of template instantiation)

make dependabot happy

(redraw)

fix #2585

allow more than one request, until lwip api rejects the call

see #2550

see #2582

separate convesions from the main source to allow test builds
extra unit to verify that both duration plain input and
spec work as intended

also fix wdt triggered when unknown symbols are encountered at the end
of duration string (e.g. 10000y)

updated duration parser with a fixed type instead of just millis
separate decimal and floating point converter as well, try to avoid
possible precision loss with microseconds use