fix(android): add an implementation for Exact filter mode

Will be eventually exposed to the UI

Author: msfjarvis

app/src/main/java/app/passwordstore/util/viewmodel/SearchableRepositoryViewModel.kt

@@ -94,18 +94,19 @@ val PasswordItem.stableId: String
 enum class FilterMode {
   NoFilter,
   StrictDomain,
-  Fuzzy
+  Fuzzy,
+  Exact,
 }
 
 enum class SearchMode {
   RecursivelyInSubdirectories,
-  InCurrentDirectoryOnly
+  InCurrentDirectoryOnly,
 }
 
 enum class ListMode {
   FilesOnly,
   DirectoriesOnly,
-  AllEntries
+  AllEntries,
 }
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -219,6 +220,16 @@ constructor(
                 .toList()
                 .sortedWith(itemComparator)
             }
+            FilterMode.Exact -> {
+              prefilteredResultFlow
+                .filter { absoluteFile ->
+                  absoluteFile.relativeTo(root).path.contains(searchAction.filter)
+                }
+                .map { it.toPasswordItem() }
+                .flowOn(dispatcherProvider.io())
+                .toList()
+                .sortedWith(itemComparator)
+            }
             FilterMode.StrictDomain -> {
               check(searchAction.listMode == ListMode.FilesOnly) {
                 "Searches with StrictDomain search mode can only list files"