Explore slowness of Gramine encrypted FS mounts

[fnerdman]

1. modify geth-sgx-gramine to store DB in encrypted files

Gramine Documentation: https://gramine.readthedocs.io/en/stable/manifest-syntax.html#encrypted-files
Geth Manifest Template: https://github.com/flashbots/geth-sgx-gramine/blob/main/geth.manifest.template#L57

NOTE: geth wants to shring files during sync which is not yet supported by gramine encrypted mount points, a patch set exists: gramineproject/gramine#972
For now, use the copy database functionality to skip this problem.

2. Performance profiling

Gramine Documentation: https://gramine.readthedocs.io/en/stable/performance.html#profiling-with-perf
Example issue of how to work with Gramine team to investigate performance issues: gramineproject/gramine#853