Implemented treeview in files list

Fixes #22

src/main/kotlin/com/jetpackduba/gitnuro/Icons.kt

@@ -25,6 +25,8 @@ object AppIcons {
     const val ERROR = "error.svg"
     const val EXPAND_MORE = "expand_more.svg"
     const val FETCH = "fetch.svg"
+    const val FOLDER = "folder.svg"
+    const val FOLDER_OPEN = "folder_open.svg"
     const val GRADE = "grade.svg"
     const val HORIZONTAL_SPLIT = "horizontal_split.svg"
     const val HISTORY = "history.svg"
@@ -59,6 +61,7 @@ object AppIcons {
     const val TAG = "tag.svg"
     const val TERMINAL = "terminal.svg"
     const val TOPIC = "topic.svg"
+    const val TREE = "tree.svg"
     const val UNDO = "undo.svg"
     const val UNIFIED = "unified.svg"
     const val UPDATE = "update.svg"

src/main/kotlin/com/jetpackduba/gitnuro/git/workspace/StageByDirectoryUseCase.kt

@@ -0,0 +1,15 @@
+package com.jetpackduba.gitnuro.git.workspace
+
+import com.jetpackduba.gitnuro.system.systemSeparator
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.eclipse.jgit.api.Git
+import javax.inject.Inject
+
+class StageByDirectoryUseCase @Inject constructor() {
+    suspend operator fun invoke(git: Git, dir: String) = withContext(Dispatchers.IO) {
+        git.add()
+            .addFilepattern(dir)
+            .call()
+    }
+}

src/main/kotlin/com/jetpackduba/gitnuro/git/workspace/UnstageByDirectoryUseCase.kt

@@ -0,0 +1,15 @@
+package com.jetpackduba.gitnuro.git.workspace
+
+import com.jetpackduba.gitnuro.system.systemSeparator
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.eclipse.jgit.api.Git
+import javax.inject.Inject
+
+class UnstageByDirectoryUseCase @Inject constructor() {
+    suspend operator fun invoke(git: Git, dir: String) = withContext(Dispatchers.IO) {
+        git.reset()
+            .addPath(dir)
+            .call()
+    }
+}

src/main/kotlin/com/jetpackduba/gitnuro/preferences/AppSettings.kt

@@ -31,6 +31,7 @@ private const val PREF_DIFF_TYPE = "diffType"
 private const val PREF_DIFF_FULL_FILE = "diffFullFile"
 private const val PREF_SWAP_UNCOMMITTED_CHANGES = "inverseUncommittedChanges"
 private const val PREF_TERMINAL_PATH = "terminalPath"
+private const val PREF_SHOW_CHANGES_AS_TREE = "showChangesAsTree"
 private const val PREF_USE_PROXY = "useProxy"
 private const val PREF_PROXY_TYPE = "proxyType"
 private const val PREF_PROXY_HOST_NAME = "proxyHostName"
@@ -50,6 +51,7 @@ private const val PREF_VERIFY_SSL = "verifySsl"
 private const val DEFAULT_COMMITS_LIMIT = 1000
 private const val DEFAULT_COMMITS_LIMIT_ENABLED = true
 private const val DEFAULT_SWAP_UNCOMMITTED_CHANGES = false
+private const val DEFAULT_SHOW_CHANGES_AS_TREE = false
 private const val DEFAULT_CACHE_CREDENTIALS_IN_MEMORY = true
 private const val DEFAULT_VERIFY_SSL = true
 const val DEFAULT_UI_SCALE = -1f
@@ -67,6 +69,9 @@ class AppSettings @Inject constructor() {
     private val _swapUncommittedChangesFlow = MutableStateFlow(swapUncommittedChanges)
     val swapUncommittedChangesFlow = _swapUncommittedChangesFlow.asStateFlow()
 
+    private val _showChangesAsTreeFlow = MutableStateFlow(showChangesAsTree)
+    val showChangesAsTreeFlow = _showChangesAsTreeFlow.asStateFlow()
+
     private val _cacheCredentialsInMemoryFlow = MutableStateFlow(cacheCredentialsInMemory)
     val cacheCredentialsInMemoryFlow = _cacheCredentialsInMemoryFlow.asStateFlow()
 
@@ -165,6 +170,15 @@ class AppSettings @Inject constructor() {
             _swapUncommittedChangesFlow.value = value
         }
 
+    var showChangesAsTree: Boolean
+        get() {
+            return preferences.getBoolean(PREF_SHOW_CHANGES_AS_TREE, DEFAULT_SHOW_CHANGES_AS_TREE)
+        }
+        set(value) {
+            preferences.putBoolean(PREF_SHOW_CHANGES_AS_TREE, value)
+            _showChangesAsTreeFlow.value = value
+        }
+
     var cacheCredentialsInMemory: Boolean
         get() {
             return preferences.getBoolean(PREF_CACHE_CREDENTIALS_IN_MEMORY, DEFAULT_CACHE_CREDENTIALS_IN_MEMORY)
@@ -347,18 +361,6 @@ class AppSettings @Inject constructor() {
             _customThemeFlow.value = Json.decodeFromString<ColorsScheme>(themeJson)
         }
     }
-
-    private fun loadProxySettings() {
-        _proxyFlow.value = ProxySettings(
-            useProxy,
-            proxyType,
-            proxyHostName,
-            proxyPortNumber,
-            proxyUseAuth,
-            proxyHostUser,
-            proxyHostPassword,
-        )
-    }
 }
 
 data class ProxySettings(