CDAP-14474 Update GCP Speech transform

Update includes:
- Rename the plugin from SpeechTranslator to SpeechToText as it is not a translator
- Add description to configs
- Fix the check done during the deploy time on the inputSchema to include the audio field and it to be bytes. This was not happening before.
- The schema given by user is output schema and was being used as both input and output earlier
- Updated to pick credential file from environment
- Add Reference doc

Author: rohitsinha54

docs/SpeechToText-transform.md

@@ -0,0 +1,44 @@
+# Google Cloud Speech-to-Text Transform
+
+Description
+-----------
+This plugin converts audio files to text by using Google Cloud Speech-to-Text.
+
+Google Cloud Speech-to-Text enables developers to convert audio to text by applying powerful neural network models.
+
+Credentials
+-----------
+If the plugin is run on a Google Cloud Dataproc cluster, the service account key does not need to be
+provided and can be set to 'auto-detect'.
+Credentials will be automatically read from the cluster environment.
+
+If the plugin is not run on a Dataproc cluster, the path to a service account key must be provided.
+The service account key can be found on the Dashboard in the Cloud Platform Console.
+Make sure the account key has permission to access Google Cloud Spanner.
+The service account key file needs to be available on every node in your cluster and
+must be readable by all users running the job.
+
+Properties
+----------
+**Audio Field:** Name of the input field which contains the raw audio data in bytes.
+
+**Audio Encoding**: Audio encoding of the data sent in the audio message. All encodings support only 1 channel (mono)
+audio. Only 'FLAC' and 'WAV' include a header that describes the bytes of audio that follow the header.
+The other encodings are raw audio bytes with no header.
+
+**Sampling Rate**: Sample rate in Hertz of the audio data sent in all 'RecognitionAudio' messages.
+Valid values are: 8000-48000. 16000 is optimal. For best results, set the sampling rate of the audio source to
+16000 Hz. If that's not possible, use the native sample rate of the audio source (instead of re-sampling).
+
+**Profanity**: Whether to attempt filtering profanities, replacing all but the initial character in each filtered
+word with asterisks, e.g. "f***". If set to `false`, profanities won't be filtered out.
+
+**Language**: The language of the supplied audio as a [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt)
+language tag. Example: "en-US". See [Language Support](https://cloud.google.com/speech/docs/languages) for a list of
+the currently supported language codes.
+
+**Transcription Parts Field**: The field to store the transcription parts. It will be an array of records. Each record
+in the array represents one part of the full audio data and will contain the transcription and confidence for that part.
+
+**Transcription Text Field**: The field to store the transcription of the full audio data. It is generated using the
+transcription for each part with the highest confidence.

docs/SpeechTranslator-transform.md

@@ -11,7 +11,7 @@
  * Contains config properties common to all GCP plugins, like project id and service account key.
  */
 public class GCPConfig extends PluginConfig {
-  private static final String AUTO_DETECT = "auto-detect";
+  public static final String AUTO_DETECT = "auto-detect";
 
   @Description("Google Cloud Project ID, which uniquely identifies a project. "
     + "It can be found on the Dashboard in the Google Cloud Platform Console.")