Add token to metamask

[anxolin]

Summary

Adds a new button to add to Metamask the VCow token

To Test

1. Claim a token
2. Add it to Metamask

[github-actions]

• 🔭 GP Swap: CoW Protocol v2 Swap UI

[elena-zh]

Hey @anxolin , nice changes!
Some my notes:

1. I'd rather not to show 'Add to MM' buton when I claim on behalf on an account
   

2. 'Added to MM' is displayed when the token is not yet added/cancelled adding. Can we add some kind of a loader when it is in 'Adding' state and show 'Added' when the asction is successful/show 'Add to MM' when the action is cancelled?
   I have to notice, that the same behavior is applicable to the the button on an order placement modal.

3. I have faced an old issue repeatedly asked to add token to MM #243 which we decided not to fix: 'Added to MM' button is clickable, calls add to MM flow again

[alfetopito]

Any reason for this?

[anxolin]

sorry for including this in the PR, not a big reason tbh. I needed at first V_COW_TOKEN_MAINNET to be declared to use it for something else. Then i was not needed it any more but I just left it like that.

I think is easier to read though, but happy to roll that back if u feel is better

[anxolin]

1. I'd rather not to show 'Add to MM' buton when I claim on behalf on an account

Done!

2. 'Added to MM' is displayed when the token is not yet added/cancelled adding. Can we add some kind of a loader when it is in 'Adding' state and show 'Added' when the asction is successful/show 'Add to MM' when the action is cancelled?
   I have to notice, that the same behavior is applicable to the the button on an order placement modal.

Yes, i used the same code. We rely on Metamask API for this. I'm not sure it can be done. Anyways, I just reuse the code as a low hanging fruit. I think it's goodish enough given the big list of things we have

3. I have faced an old issue repeatedly asked to add token to MM repeatedly asked to add token to MM #243 which we decided not to fix: 'Added to MM' button is clickable, calls add to MM flow again

Same as above. We depend on MM allowing this

[anxolin]

Just a picture of it for self claiming:

[W3stside]

Approved