POC Begone delegate macros

[PolyMeilex]

Based on https://github.com/Smithay/wayland-rs/pull/699

Removes all delegate macros, as well as redundant type constraints on D

Both this PR as well as wayland-rs part attempt to be non-braking changes, the transition should be smooth :crossed_fingers:

[ids1024]

This should genuinely make adding a simple protocol to Smithay take about half as much effort as it currently does. (The less annoying half.) It's great to see we can do this without radically changing the API!

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 30.74935% with 268 lines in your changes are missing coverage. Please review.

Project coverage is 20.52%. Comparing base (b62ced7) to head (e58193b).

Files	Patch %	Lines
src/wayland/seat/pointer.rs	0.00%	33 Missing :warning:
src/wayland/pointer_gestures.rs	0.00%	17 Missing :warning:
src/wayland/pointer_constraints.rs	13.33%	13 Missing :warning:
src/wayland/dmabuf/dispatch.rs	0.00%	11 Missing :warning:
src/wayland/compositor/tree.rs	58.33%	10 Missing :warning:
src/wayland/idle_notify/mod.rs	0.00%	10 Missing :warning:
src/wayland/selection/wlr_data_control/mod.rs	16.66%	10 Missing :warning:
src/wayland/shell/xdg/decoration.rs	37.50%	10 Missing :warning:
src/wayland/dmabuf/mod.rs	30.76%	9 Missing :warning:
src/wayland/viewporter/mod.rs	18.18%	9 Missing :warning:
... and 42 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1327      +/-   ##
==========================================
- Coverage   20.55%   20.52%   -0.04%     
==========================================
  Files         158      159       +1     
  Lines       25868    25873       +5     
==========================================
- Hits         5317     5310       -7     
- Misses      20551    20563      +12     

Flag	Coverage Δ
wlcs-buffer	17.91% <28.94%> (-0.05%)	:arrow_down:
wlcs-core	17.55% <28.94%> (-0.07%)	:arrow_down:
wlcs-output	7.37% <20.67%> (-0.16%)	:arrow_down:
wlcs-pointer-input	19.37% <28.94%> (-0.06%)	:arrow_down:

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