plugins/lsp: move dartls options in a dedicated file

plugins/lsp/language-servers/dartls-settings.nix

@@ -0,0 +1,60 @@
+{
+  lib,
+  helpers,
+}:
+with lib; {
+  analysisExcludedFolders = helpers.mkNullOrOption (with types; listOf str) ''
+    An array of paths (absolute or relative to each workspace folder) that should be excluded from
+    analysis.
+  '';
+
+  enableSdkFormatter = helpers.mkNullOrOption types.bool ''
+    When set to false, prevents registration (or unregisters) the SDK formatter.
+    When set to true or not supplied, will register/reregister the SDK formatter
+  '';
+
+  lineLength = helpers.mkNullOrOption types.ints.unsigned ''
+    The number of characters the formatter should wrap code at.
+    If unspecified, code will be wrapped at 80 characters.
+  '';
+
+  completeFunctionCalls = helpers.mkNullOrOption types.bool ''
+    When set to true, completes functions/methods with their required parameters.
+  '';
+
+  showTodos = helpers.mkNullOrOption types.bool ''
+    Whether to generate diagnostics for TODO comments.
+    If unspecified, diagnostics will not be generated.
+  '';
+
+  renameFilesWithClasses = helpers.mkNullOrOption (types.enum ["always" "prompt"]) ''
+    When set to "always", will include edits to rename files when classes are renamed if the
+    filename matches the class name (but in snake_form).
+    When set to "prompt", a prompt will be shown on each class rename asking to confirm the file
+    rename.
+    Otherwise, files will not be renamed.
+    Renames are performed using LSP's `ResourceOperation` edits - that means the rename is simply
+    included in the resulting `WorkspaceEdit` and must be handled by the client.
+  '';
+
+  enableSnippets = helpers.mkNullOrOption types.bool ''
+    Whether to include code snippets (such as class, stful, switch) in code completion.
+    When unspecified, snippets will be included.
+  '';
+
+  updateImportsOnRename = helpers.mkNullOrOption types.bool ''
+    Whether to update imports and other directives when files are renamed.
+    When unspecified, imports will be updated if the client supports `willRenameFiles` requests.
+  '';
+
+  documentation = helpers.mkNullOrOption (types.enum ["none" "summary" "full"]) ''
+    The typekind of dartdocs to include in Hovers, Code Completion, Signature Help and other similar
+    requests.
+    If not set, defaults to `"full"`.
+  '';
+
+  includeDependenciesInWorkspaceSymbols = helpers.mkNullOrOption types.bool ''
+    Whether to include symbols from dependencies and Dart/Flutter SDKs in Workspace Symbol results.
+    If not set, defaults to true.
+  '';
+}