Replace "dataToken" -> "datatoken" etc, everywhere

[trentmc]

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

It's not "data token". There is no space, it's "datatoken"; It's a single word; there are several reasons for this.

v3 wasn't filly consistent this way. Let's take the opportunity to make v4 consistent, before we ship the first version.

Searching for "datatoken" in the repo reveals "dataToken" in a few places. Searching "data token" reveals more. These need fixing.
https://github.com/oceanprotocol/contracts/search?q=datatoken

Describe the solution you'd like
Everywhere in ocean.py, replace:

• "dataToken" -> "datatoken"
• "DataToken" -> "Datatoken"
• "data token" -> "datatoken"
• "data_token" -> "datatoken"
• "Data Token" -> "Datatoken"
• etc

Additional context
A "datatoken" is the ERC20 fungible token. Complementary to it is the "Data NFT", an ERC721 non-fungible token. "Data NFT" does have a space.

Related issues: ocean.py, ocean.js

[LoznianuAnamaria]

Please add your planning poker estimate with ZenHub @lacoop6tu

[alexcos20]

Make sure that baseToken remains unchanged