feat: add rustfmt config file

Signed-off-by: Xin Liu <sam@secondstate.io>

rustfmt.toml

@@ -0,0 +1,71 @@
+array_width = 60
+attr_fn_like_width = 70
+binop_separator = "Front"
+blank_lines_lower_bound = 0
+blank_lines_upper_bound = 1
+brace_style = "SameLineWhere"
+chain_width = 60
+color = "Auto"
+combine_control_expr = true
+comment_width = 80
+condense_wildcard_suffixes = false
+control_brace_style = "AlwaysSameLine"
+disable_all_formatting = false
+edition = "2021"
+emit_mode = "Files"
+empty_item_single_line = true
+enum_discrim_align_threshold = 0
+error_on_line_overflow = false
+error_on_unformatted = false
+fn_params_layout = "Tall"
+fn_call_width = 60
+fn_single_line = false
+force_explicit_abi = true
+force_multiline_blocks = false
+format_code_in_doc_comments = false
+format_macro_bodies = true
+format_macro_matchers = true
+format_strings = false
+group_imports = "Preserve"
+hard_tabs = false
+show_parse_errors = true
+ignore = []
+imports_granularity = "Crate"
+imports_indent = "Block"
+imports_layout = "Mixed"
+indent_style = "Block"
+inline_attribute_width = 0
+make_backup = false
+match_arm_blocks = true
+match_arm_leading_pipes = "Never"
+match_block_trailing_comma = false
+max_width = 100
+merge_derives = true
+newline_style = "Auto"
+normalize_comments = false
+normalize_doc_attributes = false
+overflow_delimited_expr = false
+remove_nested_parens = true
+reorder_impl_items = false
+reorder_imports = true
+reorder_modules = true
+single_line_if_else_max_width = 50
+skip_children = false
+space_after_colon = true
+space_before_colon = false
+spaces_around_ranges = false
+struct_field_align_threshold = 0
+struct_lit_single_line = true
+struct_lit_width = 18
+struct_variant_width = 35
+tab_spaces = 4
+trailing_comma = "Vertical"
+trailing_semicolon = true
+type_punctuation_density = "Wide"
+unstable_features = false
+use_field_init_shorthand = false
+use_small_heuristics = "Default"
+use_try_shorthand = false
+style_edition = "2021"
+where_single_line = false
+wrap_comments = false