[i3c] Open points around Target CCC handling

### Description

Several open points as a result of the review of https://github.com/lowRISC/opentitan/pull/31079:

- GETACCCR must be NACKed for devices that cannot assume the Controller role. To correctly handle this is a timely manner, ~~`i3c_target_ccc_rsp_t` must be extended~~ info about the Controller role capability must be made constantly available in the transceiver clock domain. [Discussion](https://github.com/lowRISC/opentitan/pull/31079/changes#r3833168400)
- For group addresses and Direct SET CCCs, target membership in groups is currently not respected. [Discussion](https://github.com/lowRISC/opentitan/pull/31079/changes#r3831816892)
- Multi-target Direct SET CCCs and Broadcast SET CCCs terminated with an Sr do not take effect due to a control signalling issue between the main Target modules. [Discussion](https://github.com/lowRISC/opentitan/pull/31079/changes#r3831816910)
- Most of what RSTACT is specified to do is currently not implemented. [Discussion](https://github.com/lowRISC/opentitan/pull/31079/changes#r3831816903)

Start by reviewing pull request 31079 and its linked discussions, then trace the Target CCC handling for GETACCCR, group membership, Direct and Broadcast SET CCCs, and RSTACT. Done means resolving each of the four listed open points and confirming the resulting Target behavior against the relevant I3C requirements.

Written by the indexing model from the issue text.