feat(backend): set user token

[peterpeterparker]

Motivation

Given that we are required to extend the dApp to allow users to enable and disable ERC20 tokens as well, we decided to take a simplistic approach - i.e., extending the current entities with a similar mechanism as the one we implemented for CustomToken by adding an "enabled" flag to UserToken. We discussed using the "custom token" types, but extending the stable tree map we already have allows us to avoid a migration at this time that does not necessarily add value for end users. This new approach also means that user tokens (ERC20) won't be added and deleted anymore in the state, which is why this PR deprecates the related function and adds a setter, again similar to the custom token approach.

Changes

• deprecate add_user_token and remove_user_token
• add set_user_token and set_many_user_tokens for Erc20 tokens. Pattern similar to "custom token" which we added recently and are using for Icrc on the IC
• add field enabled: Option<bool> in UserToken type
• assert that the field is set when tokens are provided
• generate did and js types
• add a TODO in frontend code already resolved with all the waiting draft PRs

Notes

In another PR soon, I'll remove the deprecated functions.

Tests

Provide related tests and upgrade as well.

[peterpeterparker]

This PR blocks several other PRs (#1557, #1566, #1570, #1572, #1573, #1574), which are all blocking each other and conflicting with the realization of #1568 and #1578.

As a result, it has become too cumbersome to develop the expected features based on the draft work. That's why I am merging this PR.

Please, @bitdivine, review it as it was not merged yet, and let's improve or correct what's needed in separate PRs afterward.

[bitdivine]

LGTM, thanks. There are a couple of small tweaks that could be made but that is all.