Problem

current content.rs was a huge 520 LOC file which is not so easy to maintain and has misleading name because this file contains templates

Solution

• rename content.rs into templates module
• extract each module into dedicated file
• simplify naming for minimal generation: templates::minimal_templates::minimal_cargo_toml(...) -> templates::minimal::cargo_toml(...)
• fix println_empty_string clippy warning

cc @A91y