[feat] Deposit reward when adding new template

[TAdev0]

• issue [feat] Template ERC20 rewards deposit #30
• follows contribution guide
• code change includes tests
• breaking change

Resolves #30

[TAdev0]

@b-j-roberts here is a first draft.

Tests dont pass for now beause we need to deploy some mock erc20 contract in test to make the transfer work.

Can you give me more precisions, is anyone allowed to call add_template ? Should I add storage variables to keep track of template ids -> reward amount / reward token ?

[b-j-roberts]

Can you give me more precisions, is anyone allowed to call add_template ? Should I add storage variables to keep track of template ids -> reward amount / reward token ?

Yes, anyone can call add_template no changes are needed other than depositing the reward token.
reward and reward_token are already defined within the TemplateMetadata, so there is no need to add extra variables or storage.

[b-j-roberts]

Tests dont pass for now beause we need to deploy some mock erc20 contract in test to make the transfer work.

If you don't mind doing that as part of this PR, here is a decent ERC20 mock from another project. https://github.com/keep-starknet-strange/succinct-starknet/blob/main/src/mocks/erc20_mock.cairo

[TAdev0]

@b-j-roberts sure i'll add test , was just waiting for precisions before implementing them