feat: Implement trust boundary lookup and caching for Service Account credentials

[BigTailWolf]

We are going to implement support for service account credentials trust boundary via a cache value.

Usage of the Value

Whenever we apply a credentials to a request header, after we apply the authorization header with access_token, we are going to check the trust boundary value. If the trust boundary value is not None, we apply a header x-allowed-locations with the trust boundary value.

Update of the Value

There are two ways we can do the update of the value:

• Injection: Provide a direct setter/getter to the trust boundary value.

• Trust boundary lookup: We are not going to include in this change since the global lookup endpoint is not launched yet.

[clundin25]

@BigTailWolf is this PR ready for another round of review?

[BigTailWolf]

Hi @clundin25 and @lsirac , I removed the global lookup flow in the refresh. Now we only do supports on injection.

[BigTailWolf]

Hi @clundin25 , I'm going to close this change as I got an update on the change from backend on their design.