feat: dynamic instance image selector + use GET /instances/types so build the selector

[dni]

• think about having :latest and :v1.5.2 latest-rc

[dni]

example from saas-dev will be returned from GET /instance/types

        - lnbits/lnbits:latest-rc
        - lnbits/lnbits:latest
        - lnbits/lnbits:v1.5
        - lnbits/lnbits-sparkl2:latest-rc
        - lnbits/lnbits-sparkl2:latest

[dni]

https://api.dev.lnbits.com/instance/types

[
  {
    "tag": "lnbits/lnbits-sparkl2:latest",
    "label": "LNbits + Spark L2 Stable (latest)"
  },
  {
    "tag": "lnbits/lnbits-sparkl2:latest-rc",
    "label": "LNbits + Spark L2 Experimental (latest-rc)"
  },
  {
    "tag": "lnbits/lnbits:latest",
    "label": "LNbits Stable (latest)"
  },
  {
    "tag": "lnbits/lnbits:latest-rc",
    "label": "LNbits Experimental (latest-rc)"
  }
]```