Processing metadata tools

[alexbruy]

Description

Add a few more native algorithms to deal with layer metadata:

• Add history metadata to add a new history entry to existing entries defined for a layer
• Update layer metadata to copy non-empty metadata fields from input layer to a target layer and keeping empty fields from input unchanged in the target
• Set metadata fields to set simple metadata fields (identifier, parent identifier, title, type, encoding, language, crs, abstract, fees)

Followup #59411.

[qgis-bot]

@alexbruy
This pull request has been tagged as requiring documentation.

A documentation ticket will be opened at https://github.com/qgis/QGIS-Documentation when this PR is merged.

Please update the description (not the comments) with helpful description and screenshot to help the work from documentors.
Also, any commit having [needs-doc] or [Needs Documentation] in will see its message pushed to the issue, so please be as verbose as you can.

Thank you!

[github-actions]

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[nyalldawson]

Awesome!! 😄

[qgis-bot]

@alexbruy
A documentation ticket has been opened at qgis/QGIS-Documentation#9489
It is your responsibility to visit this ticket and add as much detail as possible for the documentation team to correctly document this change.
Thank you!