Enable a few more clippy lints (#8064)

Enable these new clippy lints and fix all warnings:

* `format_push_string` — use `write!` instead of `s += &format!(…)` to
avoid extra allocations
* `ignored_unit_patterns` — use `()` instead of `_` when matching unit
* `missing_fields_in_debug` — ensure manual `Debug` impls account for
all fields
* `needless_raw_string_hashes` — remove unnecessary `r#` on string
literals
* `ref_option` — prefer `Option<&T>` over `&Option<T>` in function
signatures

Cargo.toml

@@ -218,10 +218,12 @@ flat_map_option = "warn"
 float_cmp_const = "warn"
 fn_params_excessive_bools = "warn"
 fn_to_numeric_cast_any = "warn"
+format_push_string = "warn"
 from_iter_instead_of_collect = "warn"
 get_unwrap = "warn"
 if_let_mutex = "warn"
 ignore_without_reason = "warn"
+ignored_unit_patterns = "warn"
 implicit_clone = "warn"
 implied_bounds_in_impls = "warn"
 imprecise_flops = "warn"
@@ -270,6 +272,7 @@ mismatching_type_param_order = "warn"
 missing_assert_message = "warn"
 missing_enforced_import_renames = "warn"
 missing_errors_doc = "warn"
+missing_fields_in_debug = "warn"
 missing_safety_doc = "warn"
 mixed_attributes_style = "warn"
 mut_mut = "warn"
@@ -279,6 +282,7 @@ needless_continue = "warn"
 needless_for_each = "warn"
 needless_pass_by_ref_mut = "warn"
 needless_pass_by_value = "warn"
+needless_raw_string_hashes = "warn"
 negative_feature_names = "warn"
 non_std_lazy_statics = "warn"
 non_zero_suggestions = "warn"
@@ -299,6 +303,7 @@ rc_mutex = "warn"
 readonly_write_lock = "warn"
 redundant_type_annotations = "warn"
 ref_as_ptr = "warn"
+ref_option = "warn"
 ref_option_ref = "warn"
 ref_patterns = "warn"
 rest_pat_in_fully_bound_structs = "warn"