[Feature Request] Allow `Response - Body Attribute` tag to get populated by multiple requests

**Is your feature request related to a problem? Please describe.**

We prepared several requests pointing to the same resource and creating an object, but with different data (simplest case, regular case, complex case). Each response returns object ID we would like to use in subsequent requests. However, it is currently possible to create an environment variable just from one request.

**Describe the solution you'd like**

We would like to be able to select multiple requests when defining the value of an environment variable using a `Response - Body Attribute` tag.

No files or tests are named. Start by locating the implementation of the `Response - Body Attribute` tag and the environment-variable editor, then trace how a single request is selected and resolved. Done means users can select multiple requests for one tag and each response can supply the requested attribute for subsequent requests.

Written by the indexing model from the issue text.