feat: allow to provide log's "directives" via init_subscribers_and_loglevel

[davidB]

• so log's level filter could be defined by parameter (without need to override RUST_LOG env variable on caller side
• remove use of std::env::set_var (in the lib, and maybe on caller side) that becomes unsafe since rust 1.85

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ EDITORCONFIG	editorconfig-checker	2		0	0.01s
✅ REPOSITORY	checkov	yes		no	9.98s
✅ REPOSITORY	dustilock	yes		no	0.0s
✅ REPOSITORY	gitleaks	yes		no	0.62s
✅ REPOSITORY	git_diff	yes		no	0.01s
✅ REPOSITORY	grype	yes		no	9.78s
✅ REPOSITORY	secretlint	yes		no	0.68s
✅ REPOSITORY	syft	yes		no	1.14s
✅ REPOSITORY	trivy-sbom	yes		no	0.07s
✅ REPOSITORY	trufflehog	yes		no	1.58s

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