sidekick: fix xref link to escaped methods

[coryan]

When the method is escaped we get warnings like this:

warning: '`get`(request:options:)' doesn't exist at '/GoogleCloudComputeV1/ImagesClient'
   --> ../images+Requests.swift:135:61-135:84
133 |     }
134 |
135 +     /// Synthetic request message for the [get()][google.cloud.compute.v1.images.get] method.
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'get(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'getIamPolicy(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'getFromFamily(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'delete(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'insert(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'list(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'deprecate(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'setLabels(request:options:)'
    |                                                             ├─suggestion: Replace '`get`(request:options:)' with 'patch(request:options:)'
    |                                                             ╰─suggestion: Replace '`get`(request:options:)' with 'setIamPolicy(request:options:)'
136 |     ///
137 |     /// [google.cloud.compute.v1.images.get]: <doc:ImagesClient/`get`(request:options:)>

Changing xref link to this fixes the warning:

137 |     /// [google.cloud.compute.v1.images.get]: <doc:ImagesClient/get(request:options:)>