repo: use PlugInfo and SlotInfo for permanent plugs/slots

[stolowski]

This is part of the changes outlined in the forum here: https://forum.snapcraft.io/t/preparing-the-interfaces-logic-for-connection-hooks/2184 (item no. 7). With this change all permanent plugs and slots method take PlugInfo and SlotInfo instead of Plug and Slot (which are going to be phased out as part of refactoring of interfaces code, a few more PRs will follow).

[codecov-io]

Codecov Report

❗️ No coverage uploaded for pull request base (master@0dbad11). Click here to learn what that means.
The diff coverage is 68.14%.

@@            Coverage Diff            @@
##             master    #4120   +/-   ##
=========================================
  Coverage          ?   75.72%           
=========================================
  Files             ?      437           
  Lines             ?    37867           
  Branches          ?        0           
=========================================
  Hits              ?    28674           
  Misses            ?     7192           
  Partials          ?     2001

Impacted Files	Coverage Δ
interfaces/core.go	97.43% <ø> (ø)
interfaces/ifacetest/spec.go	5.88% <0%> (ø)
interfaces/builtin/bool_file.go	56.66% <0%> (ø)
interfaces/ifacetest/testiface.go	20.31% <0%> (ø)
interfaces/builtin/common.go	63.15% <0%> (ø)
interfaces/builtin/location_control.go	48.48% <0%> (ø)
interfaces/builtin/ubuntu_download_manager.go	31.25% <0%> (ø)
interfaces/builtin/location_observe.go	48.48% <0%> (ø)
interfaces/mount/spec.go	89.74% <100%> (ø)
interfaces/builtin/mir.go	80.55% <100%> (ø)
... and 28 more

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[zyga]

LGTM

The bug in the ofono interface is something that needs to be fixed in 2.29. I'll propose a PR for that.

[zyga]

All the changes above are ok. Can you add a test that checks we are not merging any new interfaces with the old signature methods please?

[zyga]

On second thought #4124 ensures this directly so please just merge it here after it lands in master.

[zyga]

Whoops, did this never work before!?
Perhaps we need a test that ensures that all of the known functions have the expected signatures.

[zyga]

This is now addressed in #4124

[zyga]

Please land #4124 before merging this one.

[mvo5]

This looks good (and quite mechanical). If this is the agreed direction we should land this to avoid conflicts (as it touches a lot of files).