Utility to convert restconf style path to cps path

Utility to convert restconf style path to cps path

- resource-identifier in passthrough request has restconf style path for
  the devices
- when listening cm avc event on successfull write operation , ncmp has
  to update the cache, hence the path needs to be converted to cps path
  to reuse cps-core services
- added testware to support this
- actual usage of this utility is in the next patch
- for simplicity, utility supports just one key in the path

Issue-ID: CPS-2759
Change-Id: Id3b6e629d134abc0c6b21117f5f157da90248dee
Signed-off-by: mpriyank <priyank.maheshwari@est.tech>