scripts: gen-uuid-reg.py: Generate string identifier for toml files

[softwarecki]

Extend the script that generates the uuid-registry.h file to also generate definitions containing the uuid as a string. These definitions (UUIDREG_STR_...) can be used in toml files, allowing get values from the uuid-registry.

After merge, uuid-registry.h will contain following entries:

#define _UUIDREG_dcblock { 0xb809efaf, 0x5681, 0x42b1, { 0x9e, 0xd6, 0x04, 0xbb, 0x01, 0x2d, 0xd3, 0x84 } }
#define UUIDREG_STR_DCBLOCK "b809efaf-5681-42b1-9ed6-04bb012dd384"

For example, following toml file fragment:

	[[module.entry]]
	name = "DCBLOCK"
	uuid = "B809EFAF-5681-42B1-9ED6-04BB012DD384"

will be possible to change to:

	[[module.entry]]
	name = "DCBLOCK"
	uuid = UUIDREG_STR_DCBLOCK

Require update sign.py on Zephyrs side: zephyrproject-rtos/zephyr#84615

[softwarecki]

SOFCI TEST

[softwarecki]

@kv2019i I didn't express myself clearly in the PR description. The change from Zephyr's side is not required before merging this PR. It was initially thought to be necessary for the entire functionality to work. Can we proceed with merging this PR?