Restore auto-commit after failed queries and inserts on JDBC connections

[DG47]

Closes #287.

The rollback added to BatchedQuery (and BatchedInsert) in v7 ends the failed transaction, but auto-commit is left switched off afterwards. From then on the connection runs inside an open transaction, so the next failing statement aborts it and every following statement on Postgres fails with:

org.postgresql.util.PSQLException: ERROR: current transaction is aborted, commands ignored until end of transaction block

Reproduction on develop (Postgres 16, PostgreSQL JDBC 42.3.10):

con <- connect(connectionDetails)
try(querySql(con, "SELECT * FROM no_such_table;"))
rJava::.jcall(con@jConnection, "Z", "getAutoCommit")
#> [1] FALSE

DBI::dbExecute(con, "CREATE TABLE t1 (x INT)")   # never committed
try(executeSql(con, "INSERT INTO no_such_table VALUES (1);"))
executeSql(con, "CREATE TABLE t2 (x INT);")
#> Error: ... current transaction is aborted, commands ignored until end of transaction block
querySql(con, "SELECT COUNT(*) FROM t1;")
#> Error: ... current transaction is aborted, commands ignored until end of transaction block
querySql(con, "SELECT COUNT(*) FROM t1;")
#> Error: ... relation "t1" does not exist

The same state is left behind by a failed insertTable() (for example a NOT NULL violation), and by an error raised while fetching a later batch of a query result. That last case did not roll back at all.

Changes:

• BatchedQuery: on an error, either when executing the query or while fetching a batch, roll back (only when auto-commit is off) and switch auto-commit back on. The fetch loop is moved unchanged into a private fetchRows() so the diff stays small.
• BatchedInsert: switch auto-commit back on after the existing rollback in executeBatch() and executeBigQueryBatch().
• Rebuilt inst/java/DatabaseConnector.jar (only BatchedQuery.class and BatchedInsert.class replaced, compiled with javac --release 8, class file version 52 like the existing jar) and updated inst/csv/jarChecksum.txt.
• New tests/testthat/test-errorRecovery.R. For every test server it checks that the connection still works after a failed query and after a failed insert: auto-commit is back on, and a failing executeSql() does not break the following query. On Postgres it also covers an error raised in a later fetch batch.

Testing:

• New tests against a local Postgres 16 container plus SQLite and DuckDB: 4 failures on develop, all pass with this change.
• Full testthat suite with Postgres (Eunomia GiBleed loaded into a cdm schema), SQLite and DuckDB: the only remaining failures are the two test-dbplyr.R errors, which happen the same way on develop (local data types and the installed bigrquery version).
• R CMD check --no-manual --ignore-vignettes: Status: OK.

NEWS.md is left for the maintainer.