samples: subsys: ipc: icmsg: add nRF54H20DK with PPR remote

[hasheddan]

Adds support for nRF54H20DK with the PPR VPR processor configured as the remote.

Example output for cpuapp:

[00:00:00.162,775] <inf> host: IPC-service HOST demo started
[00:00:00.162,834] <inf> host: Ep bounded
[00:00:00.162,853] <inf> host: Perform sends for 1000 [ms]
[00:00:01.162,043] <inf> host: Sent 416320 [Bytes] over 1000 [ms]
[00:00:01.162,049] <inf> host: Wait 500ms. Let remote core finish its sends
[00:00:01.662,109] <inf> host: Received 10000 [Bytes] in total
[00:00:01.662,122] <inf> host: IPC-service HOST demo ended

Example output for cpuppr:

[00:00:00.138,825] <inf> remote: IPC-service REMOTE demo started
[00:00:00.163,247] <inf> remote: Ep bounded
[00:00:01.162,155] <inf> remote: Perform sends for 1000 [ms]
[00:00:02.162,185] <inf> remote: Sent 20000 [Bytes] over 1000 [ms]
[00:00:02.162,285] <inf> remote: Received 416280 [Bytes] in total
[00:00:02.162,311] <inf> remote: IPC-service REMOTE demo ended