net: nrf_cloud_fota_poll: Add API to apply FOTA images

[simensrostad]

Add API to apply FOTA images for asyncronous use.

[github-actions]

After documentation is built, you will find the preview for this PR here.

Preview links for modified nRF Connect SDK documents:

https://ncsdoc.z6.web.core.windows.net/PR-20545/nrf/releases_and_maturity/releases/release-notes-changelog.html

[NordicBuilder]

CI Information

^{To view the history of this post, clich the 'edited' button above}
Build number: 4

Inputs:

Sources:

more details

Github labels

Enabled	Name	Description
	ci-disabled	Disable the ci execution
	ci-all-test	Run all of ci, no test spec filtering will be done
	ci-force-downstream	Force execution of downstream even if twister fails
	ci-run-twister	Force run twister
	ci-run-zephyr-twister	Force run zephyr twister

List of changed files detected by CI (0)

Outputs:

Toolchain

Version:
Build docker image:

Test Spec & Results: ✅ Success; ❌ Failure; 🟠 Queued; 🟡 Progress; ◻️ Skipped; ⚠️ Quarantine

• ❌ Toolchain
• ❌ Build twister
• ❌ Integration tests

Note: This message is automatically posted and updated by the CI