allow other platforms to call respective mining workers api

[cosmicpsyop]

To address issue raised in #484

Worker metrics

Add the following define to the platform specific header to enable API to retrieve worker metrics

// calls api to retrieve worker metrics
#define SCREEN_WORKERS_ENABLE (1)

Fees Data (Proposed and requires code reorg utilize)

Add the following define to the platform specific header to future use of fees data

// retrieve current btc fees data
#define SCREEN_FEES_ENABLE (1)

Current supported mining sites

proposed title,   entered path,    api endpoint
"public-pool.io","public-pool.io", "https://public-pool.io:40557/api/client/"
"nerdminers.org", "nerdminers.org", "https://pool.nerdminers.org/users/"
"sethforprivacy.com", "pool.sethforprivacy.com", "https://pool.sethforprivacy.com/api/client/"
"public-pool.io","http://" + Umbrel or Start9 ip address + ":2019/api/client/"  // Local instance of public-pool.io on Umbrel or Start9

Note: vkbit pool was removed from mem worker API discovery because #410

To test for API availability:

$ curl https://public-pool.io:40557/api/client/
{"workersCount":0,"workers":[]}          

See this video>> for how it works with lower screen and battery