implement mint conversions (#1930)

Implement conversions for [mint](https://docs.rs/mint) (math interoperability standard types).

- `impl From<mint::Point2> for {Physical, Logical}Position`
- `impl From<{Physical, Logical}Position> for mint::Point2`

- `impl From<mint::Vector2> for {Physical, Logical}Size`
- `impl From<{Physical, Logical}Size> for mint::Vector2`

Cargo.toml

@@ -31,6 +31,7 @@ log = "0.4"
 serde = { version = "1", optional = true, features = ["serde_derive"] }
 raw-window-handle = "0.3"
 bitflags = "1"
+mint = { version = "0.5.6", optional = true }
 
 [dev-dependencies]
 image = "0.23.12"