Set cache rebuild process indicator for the Cacti UI (poller cache and SNMPAgent cache)

[PonomarenkoVladimir]

Is your feature request related to a problem? Please describe. When I start the process of rebuilding cache poller or SNMPAgent cache, I do not see the process start, which is why I can click the mouse several times. Perhaps this may lead to a repeated launch of the cache rebuilding process.

Describe the solution you'd like I ask you to set an indicator of the cache restructuring process.

[TheWitness]

Might want to bump this one up. Putting back in the pipeline.

[TheWitness]

@PonomarenkoVladimir, I only did this on the Rebuild Poller Cache option. How long does the SNMP cache rebuild take for you? It should be blocking.