Add duplicate functionality to Browser connection items

[alexbruy]

Description

Add "Duplicate connection" action to the context menu of Browser connection items. This allows quickly make a copy of a connection to the same source when only a few details are differ (for example, different PostGIS database on the same server)

Funded by NaturalGIS.

[github-actions]

🪟 Windows builds ready!

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(Built from commit 3f9f069)

[nyalldawson]

These copy settings blocks like quite fragile -- i can easily picture them getting skipped when additional connection properties are added in future. Could they instead be moved to eg QgsHanaSettings so that they're in a closer place to where new settings will be added? (The same applies to the other db types)

[alexbruy]

As other db types do not have separate class to handle settings I have added method to connection classes.

[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!

[qgis-bot]

@alexbruy
A documentation ticket has been opened at qgis/QGIS-Documentation#9206
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!

[qgis-bot]

@alexbruy

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