Refactor Leopold keyboards and add support for new FC980C controller

[wlhlm]

Description

This supersedes #19734, which I unfortunately forgot about. I want to apologize to the original reviewers that graciously offered their time reviewing the original PR.

The ultimate goal of this is adding support for a new FC980C controller, but first I have to move the existing Leopold boards under a common directory and de-duplicate driver code. The steps have been broken out into individual commits.

Summary:

• move fc660c and fc980c under leopold/
  • move existing fc980c config under to hasu to make room for the new controller configs
• de-duplicate AD5258 driver
  • add I2C error handling
• de-duplicate actuation point handling code
• fix a bug introduced by fc660c/fc980c: clean up actuation point adjustment code #21964: the QMK i2c_master API has a quirk where it requires a I2C address to be shifted to the left which the old driver didn't have
• rework the actuation point API
• add ability to store actuation point value in QMK EEPROM for FC980C.
• rework the actuation point example keymap for FC980C

I'm a bit unsure about the includes. It all compiles, but not sure about the paths. The build systems seems to mush the paths together, for example both #include "ad5258.h" and #include "../../ad5258.h" seem to work so I'm not sure what's preferred here.

This incorporates all the feedback from the original PR except for the includes since the structure changed slightly, so I'm not sure how much of it is still relevant.

This will be affected by #22253, so I'll update once that is merged. Done

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[wlhlm]

Is there anything else that needs to be changed/updated here? Shall I spin out the bug fix into a separate PR (in light of the breaking changes timeline)? Otherwise the upcoming cycle will have broken AD5258 support for the FC980C/FC660C in master, though I imagine the impact will be pretty low.

Apologies for poking.

[github-actions]

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[github-actions]

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This pull request has been automatically closed because it has not had activity in the last 30 days. Please feel free to give a status update now, ping for review, or re-open when it's ready.
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