Bad style

Enable Lints against really bad style practices:

New Lints:

• always_declare_return_types: true
• avoid_annotating_with_dynamic: true
• avoid_bool_literals_in_conditional_expressions: true
• avoid_double_and_int_checks: true
• avoid_field_initializers_in_const_classes: true
• avoid_implementing_value_types: true
• avoid_js_rounded_ints: true
• avoid_multiple_declarations_per_line: true
• avoid_unused_constructor_parameters: true
• avoid_void_async: true
• cast_nullable_to_non_nullable: true
• join_return_with_assignment: true
• missing_whitespace_between_adjacent_strings: true
• noop_primitive_operations: true
• no_default_cases: true
• null_check_on_nullable_type_parameter: true
• only_throw_errors: true
• parameter_assignments: true
• prefer_asserts_in_initializer_lists: true
• prefer_asserts_with_message: true
• prefer_constructors_over_static_methods: true
• prefer_null_aware_method_calls: true
• tighten_type_of_initializing_formals: true
• unnecessary_await_in_return: true
• unnecessary_null_aware_assignments: true
• unnecessary_null_checks: true
• unnecessary_nullable_for_final_variable_declarations: true
• unnecessary_parenthesis: true
• use_is_even_rather_than_modulo: true
• use_late_for_private_fields_and_variables: true
• use_named_constants: true
• use_string_buffers: true