Add integration tests & misc improvements

This PR is huge (wayy to big - I should have split it). It adds several improvements to Sandstone. ## New formatter I removed ESLint + Prettier in favor of [BiomeJS](https://biomejs.dev/). It's much faster, handles all rules gracefully, and sorts imports. ## Integration tests This PR adds a new integration tests framework for Sandstone, that allows us to compare the actual & expected results of Sandstone commands. The following tests are currently implemented: * All commands are tested, as well as most of their subcommands - it's likely some have been missed * If/Else If/Else commands are tested * Score operations are tested ## Relative MCFunction names MCFunctions can now have a "relative" name, if their name starts with `./`: ```ts MCFunction('test', () => { // ⬇️ will be named default:test/foo MCFunction('./foo', () => ...) // especially useful in execute.run execute.as('@a').run('./callback', () => ...) // ⬆️ will be named default:test/callback }) ``` ## _.if conditions This re-implements the previously existing `_.` conditions: `_.block`, `_.blocks`, `_.biome`, `_.dimension`... ## Improved commands JSDoc with examples This PR adds documentation with real-life examples for all commands. This should hopefully help people get the hang of how all commands work. ## More exports This adds several missing exports to the top `sandstone` export (missing commands, some useful arguments) ## Lazy MCMetaCache & Smithed `MCMetaCache` & `Smithed` properties of `SandstoneCore` were doing HTTP calls, which should not IMO happen on a pure build process. The previous getters have been transformed to cached functions - the HTTP calls will only happen if the user explicitly calls them. ## Removed: namespaced objectives Objectives were forcefully namespaced, a decision I understand but disagree with. IMO we should add a 3d argument to `Objective.create` (& a 2nd to `Objective.get`) to enable/disable namespacing. In the meantime, I removed this feature. ## Bug fixes This PR fixes a lot of bugs: * within some subcommands (discovered with the tests) * nested ifs not working * `_.or` did not work when created outside a MCFunction => this was solved by introducing a dedicated `Visitor`