loader: add ota

[gibix]

This is a first porting of portenta_ota and

The main "change" is that now the ota payload contains <llext loader + padding + user sketch>

Features

• http
• https
• chunked http
• lzss compression
• example with ethernet
• example with progress download
• user callback for ota compleated

Boards

• portentah7 (compile and tested)
• opta
• giga
• c33

Step to reproduce

• build extra/ota-pack
• rebuild the core for you board
• compile an example (blink) and save the .ota file from the output dir
• run a simple http server python -m http.server 8000 in the directory that contains the sketch
• flash the bootloader
• flash the ota example sketch

[CLAassistant]

All committers have signed the CLA.

[github-actions]

Built 0.55.3-0.pr.424.63+6d33c9d8

CI run FAILED: ❌ giga, ❌ nano33ble, ❌ nano_matter, ❌ nicla_sense, ❌ nicla_vision, ❌ opta, ❌ portentac33, ❌ portentah7, ❌ unoq, ❌ ek_ra8d1, ❌ frdm_mcxn947, ❌ frdm_rw612

Artifact	Board	Core	Tests	RAM	Sketches	Warnings	Errors
❌ zephyr_contrib	ek_ra8d1	📗	❌	11.9%	2	-	2
	frdm_mcxn947	7 🏷️	❌	58.0%	2	-	2
	frdm_rw612	2 🏷️	❌	83.0%	2	-	2
❌ zephyr_main	giga	5 🏷️	❌	54.7%	58	-	58
	nano33ble	1 🏷️	❌	78.8%	30	-	30
	nano_matter	1 🏷️	❌	⚠️ 86.1%	22	-	22
	nicla_sense	2 🏷️	❌	⚠️ 87.6%	18	-	18
	nicla_vision	5 🏷️	❌	57.0%	52	-	50 (+2*)
	opta	5 🏷️	❌	57.7%	62	-	62
	portentac33	3 🏷️	❌	⚠️ 95.8%	66	-	66
	portentah7	4 🏷️	❌	58.5%	74	-	74
❌ zephyr_unoq	unoq	📗	❌	43.5%	56	-	56

Legend

Board	Test	Status description
🔥	🔥	Test run failed to complete.
❌	🔴	Test completed with unexpected errors.
⁉️	⁉️	Test was expected to fail but passed; exception entry is outdated.
✔️*	🚫	Test completed with errors, but all are known/expected.
✅*	🟡	Test completed with some warnings; no errors detected.
✅	🟢	Test passed successfully, with no warnings or errors.
🌑	🌑	Test was skipped.

Caution

zephyr_contrib is blocked due to failures on ek_ra8d1, frdm_mcxn947, frdm_rw612!

Caution

zephyr_main is blocked due to failures on giga, nano33ble, nano_matter, nicla_sense, nicla_vision, opta, portentac33, portentah7!

Caution

zephyr_unoq is blocked due to failures on unoq!