fix(stake.libre): use global ids for every scope in the stake table #1

What does this MR do?

Use global ids for stake table to avoid duplicated ids

Related issues

• Reported in mining.libre contract

Steps to test:

1. Compile the contract: run the following command in the root folder ./docker-build.sh
2. Validate sha256 of the wasm file is: 4c490735f6357929da822e4889fa8b2fdadc59895048720be3e6e82135bd920d. You can get the sha256 of a file by running: On Mac: shasum -a 256 --t <file_path>; On Linux: sha256sum <file_path>
3. If code changes looks good and wasm hash does match, update the contract.
4. Make a stake for 1 day. Store this stake index.
5. Claim the stake.
6. Make sure your stake got moved to completed scope.
7. Make a new stake and validate your stake index is greater than the stake you got on step 4.