Add support for Reth datadir snapshots

[matjazv]

What was the problem?

• This PR resolves #LISK-1684.
• This PR resolves #LISK-1395.

How was it solved?

• New script for downloading and applying Reth datadir snapshot was developed
• Existing script for Geth client was modified to use a new filename schema and has a fallback to a previous one
• Docs was updated where applicable
• README includes references to the API documentation for the Beacon/Execution clients

How was it tested?

• Test Reth datadir snapshot was uploaded to S3
• Following commands were used to test both Geth and Reth clients:
  • APPLY_SNAPSHOT=true CLIENT=geth SNAPSHOT_TYPE=datadir docker compose up --build --detach
  • APPLY_SNAPSHOT=true CLIENT=reth SNAPSHOT_TYPE=datadir docker compose up --build --detach

[sameersubudhi]

LGTM. Thank you for all the changes! 🙏