move common code into server, update tests and makefile (#2425)

* move common code into server, update tests and makefile

remove backend directory, refactor

update smoke tests

test/fixtures/dataset_config_outline.py

@@ -0,0 +1,30 @@
+f"""
+dataset:
+  app:
+    scripts: {scripts} #list of strs (filenames) or dicts containing keys
+    inline_scripts: {inline_scripts} #list of strs (filenames)
+
+  presentation:
+    max_categories: {max_categories}
+    custom_colors: {custom_colors}
+
+  user_annotations:
+    enable: {enable_users_annotations}
+    type: {annotation_type}
+    local_file_csv:
+      directory: {local_file_csv_directory}
+      file: {local_file_csv_file}
+      gene_sets_file: {local_file_csv_gene_sets_file}
+    gene_sets:
+      readonly: {gene_sets_readonly}
+
+  embeddings:
+    names: {embedding_names}
+
+  diffexp:
+    enable: {enable_difexp}
+    lfc_cutoff: {lfc_cutoff}
+    top_n: {top_n}
+
+  X_approximate_distribution: {X_approximate_distribution}
+"""