pruntime: Optional use RocksDB/redb as trie state backend

[kvinwang]

Description

This PR moves the chain storage and phat contract storage onto Gramine's encrypted file system.

Prior to this, we used an in-memory im::OrdMap as the storage backend. However, with the growing amount of on-chain data and the number of phat contracts, memory storage would quickly become unsustainable. Therefore, we considered moving the data into the file system to solve the problem of memory explosion. In this PR, we use Gramine's encrypted file system to store RocksDB as the storage backend. The modification is based on the existing software architecture and is implemented by changing the internal implementation of phala_trie_storage::TrieStorage.

In order to be compatible with the previous pruntime checkpoint, RocksDB is used only as a cache. That is to say, when pruntime takes snapshots, it will dump all the contents of RocksDB into the snapshot, and when pruntime starts, it will delete the RocksDB used last time and rebuild a new RocksDB instance from the snapshot.

To enable RocksDB, run pruntime with --db=rocksdb:

./pruntime --db=rocksdb

What have been tested

After the modification, the following compatibility tests were made:

• Checkpoint loading matrix

  	Saved from MemoryDB	Saved from RocksDB
  Load to MemoryDB	✅	✅
  Load to RocksDB	✅	✅

• Make sure the checkpoint is compatible with older pruntime versions.
• Regression test for load_proof.
• Test with contracts.
• The encryption block size is 4096.

Overhead

I attempted to synchronize Khala blocks. It took twice as long compared to using a memory database

Merging

Because this PR may affect the stability of pRuntime, let's not merge it for the time being, we need a lot of testing on some test networks to ensure its stability.

[h4x3rotab]

Sorry. Didn't get time to review it. Will do this week.