REF: rework the archive settings to add info(archive) nodes

[klauer]

Pairs with https://github.com/pcdshub/ads-ioc/pull/33

Still can generate .archive files separately, but also adds info nodes.

Example from an old test tmc:

# pragma:
#     (archive not specified in tmc)
record(bi, "fb:EM1K0:GMD:PRT:40:ALARM_OK_RBV") {
  ... 
  info(archive, "VAL")
}

# pragma:
#     archive: 2s monitor
#     archive_fields: VAL DESC
record(bi, "fb:EM1K0:GMD:PRT:40:RUN_DI_RBV") {
...  
  info(archive, "monitor 2: VAL DESC")
}