Consider making changes on the enumerations related to transaction type/subtype

[ipr0310]

Is your feature request related to a problem? Please describe.
I was studying the transaction types/subtypes and i found out the following:

On the following node request /api?requestType=getConstants

I get the transaction types with its subtypes:
Transaction Type 21 refers as Advanced Payment
Transaction Type 21 - Subtype 5 refers as Subscription Payment

I am curious why on SignumJS the Transaction Type 21 is recognized as Escrow
https://signum-network.github.io/signumjs/enums/core.transactionescrowsubtype.html

Describe the solution you'd like

• The enumeration TransactionEscrowSubtype should be renamed to TransactionAdvancedPaymentSubtype
  https://signum-network.github.io/signumjs/enums/core.transactionescrowsubtype.html

• One of the properties of the enumeration TransactionType should be updated
  The property 21 should be renamed to AdvancedPayment
  The property Escrow should not exists, it should be called AdvancedPayment
  https://signum-network.github.io/signumjs/enums/core.transactiontype.html

{
    "0": "Payment",
    "1": "Arbitrary",
    "2": "Asset",
    "20": "Mining",
    "21": "Escrow",
    "22": "AT",
    "3": "Marketplace",
    "4": "Leasing",
    "AT": 22,
    "Arbitrary": 1,
    "Asset": 2,
    "Escrow": 21,
    "Leasing": 4,
    "Marketplace": 3,
    "Mining": 20,
    "Payment": 0
  }

Describe alternatives you've considered
This is a grammatical error, it can be used as it is

Additional context
I suppose this is not a big breaking change because:

• Phoenix wallet does not have support for subscriptions
• Signum Explorer does not use SignumJS for reading transaction types
• Most modern official wallets does not have escrow support
• Classic or Neoclassic wallet does not use SignumJS

The wallets which uses SignumJS and has a account transactions/activity page may need to be updated, if they try to update the SignumJS version.

Second additional context
According to the node constants:
These are the subtypes of the type 21 (Advanced Payment)

• 0 = Escrow Creation
• 1 = Escrow sign
• 2 = Escrow Result
• 3 = Subscription Subscribe
• 4 = Subscription Cancel
• 5 = Subscription Payment

There is also subscriptions involved on this type, so it makes sense to rename it to AdvancedPayment because i think escrow is not related to subscriptions at all