Add support for receiving multipart/form-data

### Feature Summary

We would like to have native support for deserializing multipart/form-data, so form uploads can directly connect to Harper. And specifically we would like to ensure that any files in the form upload are translated to blobs.

Another important part of this is that we would likely want to support streaming the data to the resource API. This is probably an opt-in feature of resource classes. And a potentially complicating part of this is the blobs can’t currently begin to receive data until they are assigned to a table. So it is important the resource methods can be called prior to the stream completion.

### Problem This Solves

Direct uploading from web forms.

### Proposed Solution

Add support to contentTypes.ts for multipart/form-data.

### User Stories

_No response_

### Alternatives Considered

_No response_

### Priority/Impact

Medium - important but not urgent

### Examples or References

_No response_

### Additional Context

_No response_

### Are you planning to fix this issue?

No, just reporting the issue

### First-time contributor support

- [ ] I'm new to contributing and would appreciate guidance on the process
- [ ] I'd like help understanding the project structure
- [ ] I need assistance with setting up the development environment
- [ ] I'm comfortable contributing, but new to this project specifically