[doc] How to run tests against Picodata instance with PGPROTO support

1. Checkout this repo, branch picodata-jdbc-test
2. Create file build.local.properties in this repo root with the following contents:

privilegedUser=admin
privilegedPassword=P%ssw0rd
database=test
username=admin
password=P%ssw0rd
server=127.0.0.1
assumeMinServerVersion=9.0

3. Checkout picodata repo, branch max/get-rid-of-lua-entrypoints
4. Apply the attached patch picodata-jbdc-hacks.patch to picodata repo
5. Update Git submodules: git submodule update --remote --recursive sbroad
6. Build and run Picodata instance: RUST_BACKTRACE=1 cargo run -- run -i -c instance.pg.listen=0.0.0.0:5432
7. Update password for the user admin:

picodata> \set language sql
---
- true
...

picodata> ALTER USER "admin" WITH PASSWORD 'P%ssw0rd' USING md5;
---
- row_count: 1
...

8. Restart Picodata instance
9. Launch PgJDBC tests from this repo root (you need JDK installed and available in your path): ./gradlew test