Statediffing service v0.0.2 at v1.9.11

This is an internal release to enable us to work with the statediffing code using go modules. This release is rebased on top of master branch go-etheruem v1.9.11. Notice that the release tag has been updated to directly track the base geth version and also provide versioning for the statediffing code.

Changes to the statediff builder:

• Fix major bug in diffing, due to mapping nodes to common.BytesToHash(nodePath)
• Adjust to properly handle account and storage slot deletions and their side-effects
• Enable filtering of storage leaf keys in storage tries in addition to the address filtering in the state trie
• Enable turning on/off intermediate node inclusion at both the state and storage level
• Represent said deletion events with a new "Removed" diff node type
• Add new builder method for extracting entire state at a given height
• Create new unit tests on mainnet block data
• Expand previous unit tests to include tests for account and storage slot removal and their side-effects, new filtering, and more

Changes to the statediff service and api:

• Fix bug that wouldn't allow StateDiffAt requests at block 0
• Statediff builder params are no longer set at node initialization through the CLI, instead subscribers/requesters provide their own params through the ws and http endpoints
• Add new http endpoint (StateTrieAt) that allows requester to fetch all state and storage trie nodes at a provided height
• Clients can specify what other block data to include in the state object payload through the params they provide: block (header, uncles, and tx), receipts, and/or total difficulty