[FEATURE]: Add spin-off adjustment, Add possibility to include multiple adjustments.

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe.

The historical bars endpoint has these options:

- raw: no adjustments
- split: adjust price and volume for forward and reverse stock splits
- dividend: adjust price for cash dividends
- **spin-off: adjust price for spin-offs**
- all: apply all above adjustments

in the .NET sdk only these options are possible: raw,split,dividend,all.

As well, the selection is represented by ENUM, which makes it possible to only select ONE adjustment. so, for example, if I want only `split` and `spin-off` adjustments it is currently impossible.

### Describe the solution you'd like

please add also spin-off.
Would be nice to add multiple `adjustment` strings into one api request through .NET client, as enabled by the api endpoint.