RUMM-513 Validating JSON payload before sending to intake

We observe non-parseable logs sent to intake
In a certain org which has high volumes of logs,
%0.3-0.5 of all logs are not parsed properly in dashboard

Hypothesis #1
Data being read is malformed, because every malformed log has their malformed part at the very end
So if we can read the file later, we can have valid payload
This commit implements this hypothesis

Hypothesis #2
Write op corrupts the file and we need to watch write ops closely so that we can catch and recover errors
This requires major refactoring in File.swift and related files

Sources/Datadog/Core/Persistence/FileReader.swift

@@ -38,11 +38,17 @@ internal final class FileReader {
         }
     }
 
+    private static let utf8NewlineData = "\n".data(using: .utf8)!.first! // swiftlint:disable:this force_unwrapping
     private func synchronizedReadNextBatch() -> Batch? {
         if let file = orchestrator.getReadableFile(excludingFilesNamed: Set(filesRead.map { $0.name })) {
             do {
                 let fileData = try file.read()
                 let batchData = dataFormat.prefixData + fileData + dataFormat.suffixData
+                // Validate data here, return nil if corrupt
+                // NOTE: dataFormat.validate(batchData) would make more sense
+                try batchData.split(separator: Self.utf8NewlineData).forEach {
+                    try JSONSerialization.jsonObject(with: $0, options: [])
+                }
                 return Batch(data: batchData, file: file)
             } catch {
                 developerLogger?.error("🔥 Failed to read file: \(error)")