add nvtop integration and introduce GPU_COLLECTOR env var

agent/gpu_nvml_unsupported.go

@@ -13,21 +13,3 @@ func (c *nvmlCollector) init() error {
 }
 
 func (c *nvmlCollector) start() {}
-
-func (c *nvmlCollector) collect() {}
-
-func openLibrary(name string) (uintptr, error) {
-	return 0, fmt.Errorf("nvml not supported on this platform")
-}
-
-func getNVMLPath() string {
-	return ""
-}
-
-func hasSymbol(lib uintptr, symbol string) bool {
-	return false
-}
-
-func (c *nvmlCollector) isGPUActive(bdf string) bool {
-	return true
-}