Proto/CLST: fix get_total_supply view

To comply with the FA2.1 standard, the get_total_supply view should accept a token_id as input, and if the token_id does not exist, it should return zero.

Manually testing the MR

dune exec src/proto_alpha/lib_protocol/test/integration/main.exe -- --file test_clst.ml -m "get_total_supply view" or in sandbox:

octez-client run view get_total_supply on contract KT1WCsbJx996ebZfutAitHYsZ8FUZFsTdaD7 with input "0"
300000000000

octez-client run view get_total_supply on contract KT1WCsbJx996ebZfutAitHYsZ8FUZFsTdaD7 with input "1"
0

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR