Refactor main.rs into separate files

Create new `commands` mod with file for each command line option.

Create a couple more extractor files for moving 7zip and unrar methods into.

src/commands/mod.rs

@@ -0,0 +1,11 @@
+pub mod dump_cell_data;
+pub mod dump_cell_edit_counts;
+pub mod dump_mod_data;
+pub mod dump_mod_search_index;
+pub mod update;
+
+pub use dump_cell_data::dump_cell_data;
+pub use dump_cell_edit_counts::dump_cell_edit_counts;
+pub use dump_mod_data::dump_mod_data;
+pub use dump_mod_search_index::dump_mod_search_index;
+pub use update::update;