Include `VestPrice` cofiguration tool

Related: hive!987 (merged)

In this MR:

• Moved class VestPrice from hive to test-tools,
• Add to method set_vest_price, the method is available only for InitNode. Allows to set the Price.

usage:

node.set_vest_price(base=tt.Asset.Test(1), quote=tt.Asset.Vest(100))

log:

2023-08-07 14:07:41 [INFO] new vests price (wrapped) 1800.0 VESTS per 1 TESTS. (init_node.py:37)
2023-08-07 14:07:44 [INFO] Price stabilization completed. Invested: 10000000.000 TESTS in network. (init_node.py:47)
2023-08-07 14:07:44 [INFO] new vests price (real): 1799.9884527852744 VESTS per 1 TESTS (init_node.py:52)