New AddressIndexer leveraging CoinView

[quantumagi]

This is a reduced version of the earlier PR #995 with not-directly-relevant concerns split-off into separate PRs.

The PR replaces the current (LiteDB) AddressIndexer implementation and shares the CoinDb repository (LevelDb and optionally RocksDb or DBreeze).

Adding balance recording (for ALL addresses) to CoinView ensures a consistent view across available UTXO's and address balances. This is also a faster implementation than is provided by the current AddressIndexer. Only a fraction of a second (~40 ms) response time was observed to return the current balance AND ~1800 balance adjustments all the way to genesis. This does not require compaction and neither is it supported.

The cumulative balance is recorded in the Balance table and adjustments in the BalanceAdjustment table. This allows GetBalance to quickly supply the latest balance and if required a history of balances.

The code deals with the following issues:

• Indexing balances and balance changes.
• Keeping track of the height up to which balances are indexed so that address indexing can be toggled on/off without resulting in gaps and without requiring a complete re-build of the coin view/database. This logic also voids the need for any separate migration code.
• Replacing AddressIndexer with a new implementation.

Note: Similar to SQLiteWalletRepository and for best performance, the code tracks destinations (vs addresses). This requires any addresses queried to be convertible to destinations. This is assumed to be so for the current use-cases.

/// <summary>
/// Returns a combination of (height, satoshis) values with the cumulative balance up to the corresponding height.
/// </summary>
/// <param name="txDestination">The destination value derived from the address being queried.</param>
/// <returns>A combination of (height, satoshis) values with the cumulative balance up to the corresponding height.</returns>
/// <remarks>Balance updates (even when nett 0) are delivered for every height at which transactions for the address had been recorded 
/// and as such the returned heights can be used in conjunction with the block store to discover all related transactions.</remarks>
IEnumerable<(uint height, long satoshis)> GetBalance(TxDestination txDestination);

[quantumagi]

@fassadlr , can you please have a look at this as well and perhaps comment on whether this is good to merge into 1.5.