Switch from Snyk to native GitHub security scans and configure Dependabot

[vasylenko]

CodeQL docs:

• https://docs.github.com/en/code-security/how-tos/scan-code-for-vulnerabilities/manage-your-configuration/editing-your-configuration-of-default-setup
• https://docs.github.com/en/code-security/how-tos/scan-code-for-vulnerabilities/manage-your-configuration/set-code-scanning-merge-protection

Dependabot docs:

• https://docs.github.com/en/code-security/how-tos/secure-your-supply-chain/secure-your-dependencies/configuring-dependabot-security-updates
• https://docs.github.com/en/code-security/how-tos/secure-your-supply-chain/secure-your-dependencies/configuring-dependabot-version-updates
• https://docs.github.com/en/code-security/how-tos/secure-your-supply-chain/secure-your-dependencies/keeping-your-actions-up-to-date-with-dependabot

[vasylenko]

Migrated to Linear (SVA-13). Closing this issue.