Rework event logs and transaction database schema

[tudor-malene]

Why this change is needed

Event logs must be queried efficiently from the enclave, so we need to store them in normalised db tables, which are easy to index.

The normalisation has a knock-on effect, requiring some clarification of responsibilities and refactoring of transaction storage.

Transactions were stored twice in the database, loaded into memory and cached even though they were only needed during execution.

What changes were made as part of this PR

• normalise the "event_logs" table
• move logic from the database layer to the storage layer while keeping the database layer very simple and with a single responsibility
• cache the Batch Header only, and modify the usages ( this is the bulk of the changes)
• remove the batch_body table, which was really just the "batch_height"
• read the transactions from the transactions table
• when executing a batch, register a "contract change" hook, and based on that return what contracts are created.
• unrelated to the logic, but required for debugging: upgrade the github actions

PR checks pre-merging

Please indicate below by ticking the checkbox that you have read and performed the required
PR checks

• PR checks reviewed and performed

[BedrockSquirrel]

LGTM so far. Went through over the phone with Tudor too and the table structure etc. makes sense. Left a few minor comments and I'll scan through your new changes once you've dealt with the todos you added.

[BedrockSquirrel]

LGTM except for the tenscan contract count changing from 2 to 7 as discussed (the +1/+2 adjustments not quite right), and the segfault you mentioned

[BedrockSquirrel]

LGTM - looking forward to having this one in!