Improve C2d flows by separating initialize and initializeCompute

[alexcos20]

Describe the bug Right now, ordering assets for c2d job is very cumbersome, prone to a lot of errors:

• will you pay multiple providerFees. You should not
• is my algo allowed on the dataset? Pay and find out later :(
• what if I already have a valid order for dataset? I have to pay it again?
• what if I already have valid orders for all assets (including algo), but my providerFees are expired ?
• etc

Proposal:

• introduce new provider endpoint: initializeCompute. Endpoint will accept a POST json object, that looks like:

  {
  "datasets": [
   {   
          "documentId":"0x123",
         "serviceId":"0x123",
         "fileIndex":1
   },
   {   
         "documentId":"0x124",
         "serviceId":"0x123",
         "fileIndex":1,
         "orderTx":"0x234454645634"
   }],
  "algorithm":{   
         "documentId":"0x124",
         "serviceId":"0x123",
        "rawAlgo": false
   },
  "compute":{
      "env":"xxx",
     "validUntil":343343
  },
  "consumerAddress": "0x1234",
  "nonce": 1
  }

where:

• assets = array of assets with type=asset. service type can be either "access" or "download". fileIndex is optional

• • documentId = did, required if no orderTx
• • serviceId = desired service Id, required if no orderTx
• • fileIndex = optional
• • orderTx = if we already have a previous valid order

• algorithm = algorithm asset, if rawAlgo is true, then documentId and serviceId are no longer mandatory. For documentId, serviceId, orderTx, look above

• compute = compute options. Which env to use and for how long (validUntil = timestamp)

Provider will do:

• check validity of running such a scenario (is the algo allowed? can I run raw algo? it's trusted ? etc)
• check validity of orderTx (if given), to make sure that order is still valid and user doesn't have to pay again
• will output an array of orders
• if asset(algo or dataset) is served by another provider then:
• • if service type is access, reach out to remote provider, call initialize, get providerFees and pass them though
• • reject call if dataset or algo service type is compute and it's a remote provider

{
 "datasets": [
           {  "datatoken": "0x123", "providerFees": {..} }, 
           {  "validOrder": "0x234454645634", "providerFees": {..} }
           {  "validOrder": "0x4567"}
 ],
 "algorithm": { "datatoken": "0x123", "providerFees": {..} },
   "compute":{
        "env":"xxx",
       "validUntil":343343
    },
}

where:

• datasets = array of orders which needs to be executed by user.

• • if datatoken field is present, user must call startOrder and pay both 1 DT & providerFees (if providerAmount>0)
• • if validOrder field is present, and providerFees are present, user must call reuseOrder and pay only providerFees (if providerAmount>0)
• • if validOrder field is present, and no providerFees, user will use this orderId when calling provider startCompute (order is valid, providerFees are valid, so no need of any additional call)

• algorithm = order which needs to be executed by user to purchase the algo (if needed). Uses same structure as above

• compute = compute params used to call provider startCompute

Of course, ocean.js /py needs to be updated as well