perf[mask]: check AllTrue/AllFalse in eq (#8354)

If two Mask::AllTrue or AllFalse are passed we don't need a bit buffer
to check equality

Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>

Author: joseph-isaacs

vortex-mask/src/eq.rs

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: Apache-2.0
 // SPDX-FileCopyrightText: Copyright the Vortex contributors
 
+use std::mem;
+
 use crate::Mask;
 
 impl PartialEq for Mask {
@@ -9,6 +11,9 @@ impl PartialEq for Mask {
         if self.len() != other.len() {
             return false;
         }
+        if mem::discriminant(self) == mem::discriminant(other) && !matches!(self, Mask::Values(_)) {
+            return true;
+        }
         if self.true_count() != other.true_count() {
             return false;
         }