Define Acquisition method schema as controlled vocabulary

Purpose/Overview:
Acquisition method is a converted to a controlled vocabulary
Details : https://wiki.folio.org/display/ACQ/Export+FOLIO+orders+in+EDIFACT+format#ExportFOLIOordersinEDIFACTformat-Acquisitionmethodisaconvertedtoacontrolledvocabulary

Requirements/Scope:

1. Replace "acquisitionMethod" enum from mod-orders-storage/schemas/po_line.json with controlled vocabulary
2. dennisbridges What is the best place to store link on controlled "acquisitionMethod" in the POL or Order?
   From Denis : we only need to reference acquisition methods from POLs.

Approach:
1. Create migration script :
1.1. Where you should fill table "acquisition_method" with methods from enum ramls/acq-models/mod-orders-storage/schemas/po_line -> "acquisitionMethod"
1.2. Replace value of the "acquisitionMethod" field with reference on record from "acquisition_method"

2. Reference on acquisition method should store in the POL. To do this enum of methods must be replaced with UUID reference on "acquisition_method" record.

    "id": {
      "acquisitionMethod": "UUID of the acquisition method for this purchase order line",
      "$ref": "../../common/schemas/uuid.json"
    }

3. Update all samples with "acquisitionMethod" field
4. All major API versions must be updated where POL is used

Acceptance criteria:

• Schemes updated
• Sample updated/created