Publish bundle jsonschema.json as a release asset (#5083)

## Summary
- Upload `bundle/schema/jsonschema.json` (the output of `databricks
bundle schema`) as a GitHub release asset via goreleaser's
`release.extra_files`.
- Motivation: we want to register the bundle JSON schema in
[SchemaStore](https://www.schemastore.org/) pointing at a stable
"latest" release URL
(`https://github.com/databricks/cli/releases/latest/download/jsonschema.json`).
Publishing as a release asset gives us that URL so SchemaStore doesn't
need to be updated on every CLI release.

## Test plan
- [x] Verify goreleaser config parses (`goreleaser check` if available
locally, otherwise rely on the release workflow).
```
% goreleaser check
  • checking                                  path=.goreleaser.yaml
  • 1 configuration file(s) validated
  • thanks for using GoReleaser!
```
- [ ] After the next tagged release, confirm `jsonschema.json` appears
as a release asset and that
`https://github.com/databricks/cli/releases/latest/download/jsonschema.json`
resolves to it.

This pull request and its description were written by Isaac.

Author: janniklasrose

.goreleaser.yaml

@@ -66,3 +66,7 @@ changelog:
     exclude:
       - '^docs:'
       - '^test:'
+
+release:
+  extra_files:
+    - glob: bundle/schema/jsonschema.json