Plugins: Use grafana-plugin-sdk-go v0.5.0 (#21116)

* fix dispense

* plugin loading refactor

Moves common functionality of registering, starting,
stopping and restarting backend plugins to
backendplugin package.

* simplify plugin descriptors

* target sdk v0.5.0

Co-authored-by: Kyle Brandt <kyle@kbrandt.com>

vendor/github.com/prometheus/procfs/proc_limits.go

@@ -78,7 +78,14 @@ var (
 )
 
 // NewLimits returns the current soft limits of the process.
+//
+// Deprecated: use p.Limits() instead
 func (p Proc) NewLimits() (ProcLimits, error) {
+	return p.Limits()
+}
+
+// Limits returns the current soft limits of the process.
+func (p Proc) Limits() (ProcLimits, error) {
 	f, err := os.Open(p.path("limits"))
 	if err != nil {
 		return ProcLimits{}, err