typescript-rtk-query support for gqlImport

**Is your feature request related to a problem? Please describe.**
Our fragments are shared by frontend and backend so we are forced to keep them using `gql` tagged strings from `@apollo/client` The issue is that when the plugin generates the endpoints it will produce a query like this
```
export const SomeMutation = `
mutation SomeQuery($input: SomeMutationInput!) {
someMutation(input: $input) {
...SomeFragment
}
}
${TaggedStringFragment}
`
```
This at the end will result in error on the client which is interpreting the fragment as `[object][object]`

**Describe the solution you'd like**

Like other typescript plugins, supporting `documentMode` and `gqlImport` options will resolve the issue. wrapping the query with `gql` before making request won't solve the issue because it is a tagged string

**Describe alternatives you've considered**

**Additional context**

Start at the typescript-rtk-query plugin and trace how generated endpoints handle documentMode and gqlImport. Done means shared tagged-string fragments no longer become [object Object] in the generated query; the issue names no specific files or tests to run.

Written by the indexing model from the issue text.