[ Improvement ] Support Chained TR Queries

[andorsk]

First now, TRQP is a one level deep API and it would be great if we could support chaining, so a top level anchor based query can chain downstream to leafs to respond to a question.

Borrowing this topology from OIDF (below). A query from A should be able to chain down to respond to the question Does Entity X have Authorization Y, in the context of Ecosystem Governance Framework Z, when EGF Z is not managed by the provider (i.e RoR)

I have a few thoughts on how this could be done, and I will send over a PR in the future with those suggestions. For now, I am logging for future considerations.

 ----------------             -----------------
  Trust Anchor A |            |  Trust Anchor B |
'------.--.-------'            '----.--.--.------'
       |  |                         |  |  |
    .--'  '---. .-------------------'  |  |
    |         | |                      |  |
.---v.  .-----v-v------.   .-----------'  |
| OP |  | Intermediate |   |              |
'----'  '--.--.--.-----'   |    .---------v----.
           |  |  |         |    | Intermediate |
   .-------'  |  '------.  |    '---.--.--.----'
   |          |         |  |        |  |  |
.--v-.      .-v--.     .v--v.   .---'  |  '----.
| RP |      | RS |     | OP |   |      |       |
'----'      '----'     '----'   |   .--v-.   .-v--.
                                |   | RP |   | RP |
                                |   '----'   '----'
                                |
                        .-------v------.
                        | Intermediate |
                        '----.--.--.---'
                             |  |  |
                       .-----'  |  '----.
                       |        |       |
                    .--v-.   .--v-.   .-v--.
                    | OP |   | RP |   | AS |

[andorsk]

We are looking into this in conjunction with the common data model and base interaction patterns.