Backport the psql indexer into v0.34.x (#6906)

This change backports the PostgreSQL indexing sink, addressing part of #6828.

Development on the main branch has diverged substantially since the v0.34.x
release. It includes package moves, breaking API and protobuf schema changes,
and new APIs, all of which together have a large footprint on the mapping
between the implementation at tip and the v0.34 release branch.

To avoid the need to retrofit all of those improvements, this change works by
injecting the new indexing sink into the existing (v0.34) indexing interfaces
by delegation. This means the backport does _not_ pull in all the newer APIs
for event handling, and thus has minimal impact on existing code written
against the v0.34 package structure.

This change includes the test for the `psql` implementation, and thus updates
some Go module dependencies. Because it does not interact with any other types,
however, I did not add any unit tests to other packages in this change.

Related changes:
 * Update module dependencies for psql backport.
 * Update test data to be type-compatible with the old protobuf types.
 * Add config settings for the PostgreSQL indexer.
 * Clean up some linter settings.
 * Hook up the psql indexer in the node main.

docs/app-dev/indexing-transactions.md

@@ -31,24 +31,61 @@ For example:
 
 would be equal to the composite key of `jack.account.number`.
 
-Let's take a look at the `[tx_index]` config section:
+By default, Tendermint will index all transactions by their respective hashes
+and height and blocks by their height.
+
+## Configuration
+
+Operators can configure indexing via the `[tx_index]` section. The `indexer`
+field takes a series of supported indexers. If `null` is included, indexing will
+be turned off regardless of other values provided.
 
 ```toml
-##### transactions indexer configuration options #####
-[tx_index]
+[tx-index]
 
-# What indexer to use for transactions
+# The backend database to back the indexer.
+# If indexer is "null", no indexer service will be used.
+#
+# The application will set which txs to index. In some cases a node operator will be able
+# to decide which txs to index based on configuration set in the application.
 #
 # Options:
 #   1) "null"
 #   2) "kv" (default) - the simplest possible indexer, backed by key-value storage (defaults to levelDB; see DBBackend).
-indexer = "kv"
+#     - When "kv" is chosen "tx.height" and "tx.hash" will always be indexed.
+#   3) "psql" - the indexer services backed by PostgreSQL.
+# indexer = "kv"
 ```
 
-By default, Tendermint will index all transactions by their respective hashes
-and height and blocks by their height.
+### Supported Indexers
 
-You can turn off indexing completely by setting `tx_index` to `null`.
+#### KV
+
+The `kv` indexer type is an embedded key-value store supported by the main
+underlying Tendermint database. Using the `kv` indexer type allows you to query
+for block and transaction events directly against Tendermint's RPC. However, the
+query syntax is limited and so this indexer type might be deprecated or removed
+entirely in the future.
+
+#### PostgreSQL
+
+The `psql` indexer type allows an operator to enable block and transaction event
+indexing by proxying it to an external PostgreSQL instance allowing for the events
+to be stored in relational models. Since the events are stored in a RDBMS, operators
+can leverage SQL to perform a series of rich and complex queries that are not
+supported by the `kv` indexer type. Since operators can leverage SQL directly,
+searching is not enabled for the `psql` indexer type via Tendermint's RPC -- any
+such query will fail.
+
+Note, the SQL schema is stored in `state/indexer/sink/psql/schema.sql` and operators
+must explicitly create the relations prior to starting Tendermint and enabling
+the `psql` indexer type.
+
+Example:
+
+```shell
+$ psql ... -f state/indexer/sink/psql/schema.sql
+```
 
 ## Default Indexes