[FEATURE] Add Position API that does not include the token type in the API path

[purplesmoke05]

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

• Currently, Position APIs are for each token type(StraightBond, Share, Membership, Coupon).
• It may be useful to be able to get Position across token types.
  • with following response schema

class TokenPositionsResponse(BaseModel):
    result_set: ResultSet
    positions: Union[
        list[
            Union[
                StraightBondPositionWithDetail,
                SharePositionWithDetail,
                CouponPositionWithDetail,
                MembershipPositionWithDetail,
            ]
        ],
        list[
            Union[
                StraightBondPositionWithAddress,
                SharePositionWithAddress,
                CouponPositionWithAddress,
                MembershipPositionWithAddress,
            ]
        ]
    ]

Describe the solution you'd like

• Investigate and consider the need for such an API.
• Implement new Position API.