refactor(bar): use native apis for positioning

This commit replaces almost all uses of the egui Viewport API for bar
window positioning with calls to SetWindowPos via komorebi_client's
Window struct.

This seems to play much more smoothly with multi-monitor setups where
each monitor has a different scaling factor, opening the door for
multiple instances of komorebi-bar.exe to run against multiple monitors.

As a result of this change, the "viewport" configuration option has been
renamed to "position" and doc strings have been changed to remove the
reference to the egui crate docs. Similarly, "viewport.position" and
"viewport.inner_size" have been renamed to "position.start" and
"position.end" respectively. Backwards-compatibility aliases have been
included for all renames.

Cargo.lock

@@ -501,12 +501,6 @@ version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1505bd5d3d116872e7271a6d4e16d81d0c8570876c8de68093a09ac269d8aac0"
 
-[[package]]
-name = "atomic_float"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "628d228f918ac3b82fe590352cc719d30664a0c13ca3a60266fe02c7132d480a"
-
 [[package]]
 name = "atspi"
 version = "0.19.0"
@@ -2711,7 +2705,6 @@ dependencies = [
 name = "komorebi-bar"
 version = "0.1.30"
 dependencies = [
- "atomic_float",
  "chrono",
  "clap",
  "color-eyre",