### What does this PR do?
`JSPromise.rejectedPromiseValue` does not notify the VM about the promise it creates, meaning unhandled rejections created this way do not trigger `unhandledRejection`. This is leading to accidental error suppression in (likely) a lot of places. Additionally it returns a `JSValue` when really it should be returning a `*JSPromise`, making Zig bindings more type-safe.
This PR renames `rejectedPromiseValue` to `dangerouslyCreateRejectedPromiseValueWithoutNotifyingVM` and marks it as deprecated. It does _not_ modify code calling this function, meaning no behavior changes should occur. We should slowly start replacing its usages with `rejectedPromise`
## Changelog
- Rename `rejectedPromiseValue` to `dangerouslyCreateRejectedPromiseValueWithoutNotifyingVM`
- Mark `JSPromise.asValue` as deprecated. It takes a `*JSGlobalObject` but never uses it. New code should use `toJS()`
- Refactors `blob` to make null checks over `destination_blob.source` a release assertion
- `ErrorBuilder.reject` uses `rejectedPromiseValue` when 1.3 feature flag is enabled
### What does this PR do?
Lets us write and run unit tests directly in Zig.
Running Zig unit tests in CI is blocked by https://github.com/ziglang/zig/issues/23281. We can un-comment relevant code once this is fixed.
#### Workflow
> I'll finish writing this up later, but some initial points are below.
> Tl;Dr: `bun build:test`
Test binaries can be made for any kind of build. They are called `<bun>-test` and live next to their corresponding `bun` bin. For example, debug tests compile to `build/debug/bun-debug-test`.
Test binaries re-use most cmake/zig build steps from normal bun binaries, so building one after a normal bun build is pretty fast.
### How did you verify your code works?
I tested that my tests run tests.
