Add global context.cacheDir provider. (#1606)

## Type of change

- [ ] Feature
- [ ] Bugfix
- [x] Technical
- [ ] Other :

## Content

Dagger now provides the app's `cacheDir` when requesting a `@CacheDirectory File`  type.

## Motivation and context

To support some upcoming code that needs the `cacheDir` to be changed during tests.

libraries/di/src/main/kotlin/io/element/android/libraries/di/ApplicationContext.kt

@@ -18,4 +18,10 @@ package io.element.android.libraries.di
 
 import javax.inject.Qualifier
 
-@Qualifier annotation class ApplicationContext
+/**
+ * Qualifies a [Context] object that represents the application context.
+ */
+@Retention(AnnotationRetention.RUNTIME)
+@MustBeDocumented
+@Qualifier
+annotation class ApplicationContext

libraries/di/src/main/kotlin/io/element/android/libraries/di/CacheDirectory.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * 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
+ *
+ *     http://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 io.element.android.libraries.di
+
+import javax.inject.Qualifier
+
+/**
+ * Qualifies a [File] object which represents the application cache directory.
+ */
+@Retention(AnnotationRetention.RUNTIME)
+@MustBeDocumented
+@Qualifier
+annotation class CacheDirectory