TUN-8735: add managed/local log collection

## Summary
Adds a log collector for the managed/local runtimes.


Closes TUN-8735 TUN-8736

diagnostic/log_collector.go

@@ -0,0 +1,34 @@
+package diagnostic
+
+import (
+	"context"
+)
+
+// Represents the path of the log file or log directory.
+// This struct is meant to give some ergonimics regarding
+// the logging information.
+type LogInformation struct {
+	path        string // path to a file or directory
+	wasCreated  bool   // denotes if `path` was created
+	isDirectory bool   // denotes if `path` is a directory
+}
+
+func NewLogInformation(
+	path string,
+	wasCreated bool,
+	isDirectory bool,
+) *LogInformation {
+	return &LogInformation{
+		path,
+		wasCreated,
+		isDirectory,
+	}
+}
+
+type LogCollector interface {
+	// This function is responsible for returning a path to a single file
+	// whose contents are the logs of a cloudflared instance.
+	// A new file may be create by a LogCollector, thus, its the caller
+	// responsibility to remove the newly create file.
+	Collect(ctx context.Context) (*LogInformation, error)
+}