Improve snapshot restoration for blockchain node charts

[chriswessels]

• Update docker-builds/init-toolkit with a suite of download and extraction tools
• Allowing specifying custom script (with env vars for things like the persistent data path) in the initContainer that handles snapshot restoration
• Update documentation to show handling common formats with aria2c or other tools
• Document how download-resumption works

[matthewdarwin]

Also support downloading from S3 bucket, which would require AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY

[matthewdarwin]

Also support zstd and lz4 compression. Different snapshot providers use different compression algorithms. (They probably also use different directory layouts, additional challenge)