feat(griffin): cancel active read-only queries on client disconnect; added resource constraints (#396)

chore: runtime build for linux, updated questdb.sh to use both "runtime" java and JAVA_HOME depending on where it is running from (#280)

This commit also adds a new `maven` profile to keep the possibility of running
`maven` tasks without having to install `Node.js` locally`.

Documentation changes:

1. README.md

- Update requirements
- Simplify "Building & Running"
- Fix typos

2. CONTRIBUTING.md

- Update repository overview
- Update artificats creation
- Add section for Local frontend development
- Add FAQ
- Update requirements
- Fix typos

3. ui/README.md

- Coordinate changes on requirements with the rest of the documentation

There is substantial amount of API changes to allow correct framing of data for aggregation. Query model now has both sets of columns: bottom-up and top-down. Top-Down is new. Upstream code now has context of what data is needed downstream. I also fixed a few bugs along the way, too many to mention

feat(cairo): null-aware sum(double), avg(double), min(double) and max(double). These functions run on entire column.

feat(griffin): cast() implementation at parser level + bugfixes. Reference implementation for cast(int as xxx). Removed to_long(), to_int() and to_timestamp() - hence version bump to 4.1.5-SNAPSHOT

fixed issue with graceful shutdown, able to use command prompt and view logs via docker commands.

Going back to 'org.questdb' group.