Add annotation ReadPreference

[jorgerod]

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Closes: #2971

[christophstrobl]

Thank you @jorgerod for the PR we'll have a closer look asap.

[christophstrobl]

Thank you again @jorgerod for investing time into this feature and creating the PR, which looks very decent 👍

Things we'd need to consider as well are methods inherited from other repository interfaces like findAll if the actual repository interface holds a ReadPreference annotation, so that users are not forced to redeclare those in order to get the desired result.

We do feel that fine grained control, like tags, are better suited for usage with the template API/custom repositories, where one has more control over the actual query and its dynamics. Therefore we think they should not surface on the repository level.
However, having support for SpEL expressions, as we have in other places already, might be beneficial as this would allow us to register beans that can serve as ReadPreference suppliers.

[jorgerod]

Hi @christophstrobl

Sorry for the waiting time but I've been quite busy lately.

The changes you propose seem to me to be correct.
I see that you are making progress in this area.

I will follow your progress.

Thank you

[christophstrobl]

Thank you again @jorgerod for your contribution! The changes have been merged to the main development line.