Fix path normalization for Windows OS

wire-schema/src/commonMain/kotlin/com/squareup/wire/schema/Location.kt

@@ -70,7 +70,9 @@ data class Location(
       base: String,
       path: String,
     ): Location {
-      return Location(base.trimEnd('/'), path, -1, -1)
+      val normalizedBase = base.replace('\\', '/')
+      val normalizedPath = path.replace('\\', '/')
+      return Location(normalizedBase.trimEnd('/'), normalizedPath, -1, -1)
     }
   }
 }

wire-schema/src/commonTest/kotlin/com/squareup/wire/schema/LocationTest.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2024 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.wire.schema
+
+import assertk.assertThat
+import assertk.assertions.isEqualTo
+import kotlin.test.Test
+
+class LocationTest {
+
+  @Test fun getWithBaseAndRelativePath() {
+    val location = Location.get("/base/dir", "test/file.proto")
+    assertThat(location.base).isEqualTo("/base/dir")
+    assertThat(location.path).isEqualTo("test/file.proto")
+  }
+
+  @Test fun getWithWindowsStylePaths() {
+    val location = Location.get(
+      "C:\\Users\\protoDir",
+      "languageDir\\language.proto",
+    )
+    assertThat(location.base).isEqualTo("C:/Users/protoDir")
+    assertThat(location.path).isEqualTo("languageDir/language.proto")
+  }
+}