feat: change mut ref to ref in the parameters of get_roles_for_user and other similar functions.

[liulifox233]

• resolve: Why does get_roles_for_user take a &mut ref? #341
• feat: remove empty line after doc comments in enforce_with_context to fix warning in cargo-clippy.

[github-actions]

Benchmark for c5a05d3

Click to view benchmark

Test	PR Benchmark	Master Benchmark	%
b_benchmark_rbac_model_large	10.1±0.09ms	9.8±0.11ms	+3.06%
benchmark priority model	4.1±0.05µs	4.1±0.04µs	0.00%
benchmark_abac_model	2.4±0.03µs	2.4±0.06µs	0.00%
benchmark_basic_model	3.6±0.06µs	3.7±0.04µs	-2.70%
benchmark_key_match	6.7±0.21µs	6.7±0.12µs	0.00%
benchmark_raw	0.0±0.00ns	0.0±0.00ns	NaN%
benchmark_rbac_model	5.9±0.09µs	5.9±0.09µs	0.00%
benchmark_rbac_model_medium	843.7±18.22µs	836.6±5.98µs	+0.85%
benchmark_rbac_model_with_domains	5.8±0.21µs	5.8±0.09µs	0.00%
benchmark_rbac_with_deny	8.3±0.13µs	8.3±0.11µs	0.00%
benchmark_rbac_with_resource_roles	4.2±0.11µs	4.2±0.04µs	0.00%
benchmark_role_manager_large	4.6±0.03ms	4.6±0.01ms	0.00%
benchmark_role_manager_medium	295.7±4.38µs	295.7±5.60µs	0.00%
benchmark_role_manager_small	88.0±2.88µs	89.7±2.40µs	-1.90%

[github-actions]

Benchmark for c5a05d3

Click to view benchmark

Test	PR Benchmark	Master Benchmark	%
b_benchmark_rbac_model_large	9.7±0.08ms	9.8±0.20ms	-1.02%
benchmark priority model	4.3±0.06µs	4.3±0.07µs	0.00%
benchmark_abac_model	2.4±0.02µs	2.5±0.02µs	-4.00%
benchmark_basic_model	3.8±0.05µs	3.8±0.05µs	0.00%
benchmark_key_match	7.0±0.10µs	6.8±0.13µs	+2.94%
benchmark_raw	0.0±0.00ns	0.0±0.00ns	NaN%
benchmark_rbac_model	6.3±0.14µs	6.2±0.09µs	+1.61%
benchmark_rbac_model_medium	858.7±7.87µs	843.0±9.01µs	+1.86%
benchmark_rbac_model_with_domains	6.0±0.08µs	6.0±0.07µs	0.00%
benchmark_rbac_with_deny	8.6±0.92µs	8.4±0.10µs	+2.38%
benchmark_rbac_with_resource_roles	4.4±0.08µs	4.4±0.04µs	0.00%
benchmark_role_manager_large	4.6±0.03ms	4.7±0.05ms	-2.13%
benchmark_role_manager_medium	299.0±3.55µs	297.7±2.46µs	+0.44%
benchmark_role_manager_small	88.6±1.15µs	87.3±0.81µs	+1.49%