Figure out how to call BlueAPI plans using their direct entry point

From today's discussed between @noemifrisina and I

We currently need an extra entry point for each BlueAPI plan that will be called by the web GUI (see https://github.com/DiamondLightSource/mx-bluesky/pull/1565). The only difference between this new entry point and the other one that it calls is that the params pydantic model is separated out into individual parameters.

There are two reasons for this:
1. BlueAPI isn't happy with post requests which just send a json blob -it will complain about types. (This might be fixed now, part of this issue is confirming this)
2. We don't know how to construct our "params" object in type script

## Acceptance Criteria
1. Confirm that 1.) above is still a problem. If it is, push for a fix
2. Figure out how to construct params in typescript and do this change. I'm sure it's possible, but I don't know much typescript
3. Implement changes and remove duplicated entry points

Start with the web-GUI integration described in PR #1565 and inspect the existing BlueAPI plan entry point and the additional direct entry point described here. Confirm whether BlueAPI still rejects POST requests containing a JSON params object, then determine how the params model is constructed in TypeScript. Done means the required entry point works and duplicated entry points are removed.

Written by the indexing model from the issue text.