Provide client specific scope,grant_type and empty secret code options to get IMS token in the spacecat-shared-ims-client package

**Is your feature request related to a problem? Please describe.**
Right now the function getServiceAccessToken() does not have options to send different grant_type, scope and no client_code, which we need for Adobe Analytics API access.

**Describe the solution you'd like**
The function getServiceAccessToken at https://github.com/adobe/spacecat-shared/blob/3130218762e469cae6b613f1593830b096bc0f52/packages/spacecat-shared-ims-client/src/clients/ims-client.js#L183 should support to pass user specific scope, grant_type and no code.

**Describe alternatives you've considered**
May be an override function to getServiceAccessToken, where user can pass scope and grant_type and node client_code.

**Additional context**
Add any other context or screenshots about the feature request here.

Start in packages/spacecat-shared-ims-client/src/clients/ims-client.js at getServiceAccessToken around line 183, and inspect how its current token request is assembled. The change is complete when callers can provide a scope and grant_type and request a token without a client_code for Adobe Analytics API access.

Written by the indexing model from the issue text.