feat: Add new method `IsBlock::declared_style` #623

Job	Run time
Unit tests with minimum versions of direct dependencies (windows-latest)	57s
Unit tests with minimum versions of direct dependencies (macos-latest)	29s
Unit tests with minimum versions of direct dependencies (ubuntu-latest)	17s
Preflight crate publish (ubuntu-latest, stable)	30s
Clippy	9s
Unit tests (windows-latest, stable)	1m 35s
Unit tests (windows-latest, 1.74.0)	1m 16s
Unit tests (macos-latest, stable)	27s
Test performance on benchmarks	38s
Unit tests (macos-latest, 1.74.0)	34s
Enforce Rust code format	12s
Unit tests (ubuntu-latest, stable)	30s
Unit tests (ubuntu-latest, 1.74.0)	24s
License / vulnerability audit (advisories)	17s
License / vulnerability audit (bans licenses sources)	20s
Preflight docs.rs build	14s
Generate spec coverage	27s
Check for unused dependencies	27s
	9m 43s

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