Add support for new decoders of Fluendo

Fluendo divided their decoders by backend and codec, so where before there
were just `fluhwvadec` or `fluhwvah264dec`, now there are
`fluhwva{backend}{codec}` (`fluhwvavaapih264dec` for example).

This commit generate the types for this decoders programmatically, to
reduce the amount of code required otherwise.

Issue: OCP_5454

fluster/decoders/gstreamer.py

@@ -912,3 +912,46 @@ class FluendoFluLCEVCVAH264DecGst10Decoder(GStreamer10Video):
     api = "HW"
     hw_acceleration = True
     name = f"{provider}-{codec.value}-{api}-lcevchwvah264dec-Gst1.0"
+
+# Auxiliary function for generate a H264 Fluendo decoder based on the HW API
+def new_fluhwvah264dec(api: str):
+    new_class_name = f"FluendoHWVA{api}H264Gst10Decoder"
+
+    new_class = type(new_class_name, (GStreamer10Video,), {})
+    new_class.provider = "Fluendoo"
+    new_class.api = api
+    new_class.codec = Codec.H264
+    new_class.decoder_bin = f" h264parse ! fluhwva{api.lower()}h264dec "
+
+    register_decoder(new_class)
+
+# Auxiliary function for generate a H265 Fluendo decoder based on the HW API
+def new_fluhwvah265dec(api: str, strict_format: str, alignment: str):
+    new_class_name = f"FluendoHWVA{api}H265Gst10Decoder"
+
+    def __init__(self):
+        super(GStreamer10Video, self).__init__()
+        variant = f"{self.codec.value}-{self.stream_format}-{self.alignment}"
+        self.name = f"{self.provider}-{variant}-{self.api}-Gst{self.gst_api}"
+        self.description = f"{self.provider} {variant} {self.api} decoder for GStreamer {self.gst_api}"
+
+    new_class = type(new_class_name, (GStreamer10Video,), {"__init__": __init__})
+    new_class.provider = "Fluendo"
+    new_class.api = api
+    new_class.codec = Codec.H265
+    new_class.stream_format = stream_format
+    new_class.alignment = alignment
+    new_class.decoder_bin = (
+        " h265parse !"
+        f" video/x-h265,stream-format={stream_format},alignment={alignment} !"
+        f" fluhwva{api.lower()}h265dec "
+    )
+
+    register_decoder(new_class)
+
+# Generate all Fluendo decoders variants for H264 and H265
+for api in ["VAAPI", "VDPAU", "DXVA2", "VDA", "VT"]:
+    new_fluhwvah264dec(api)
+    for stream_format in ["byte-stream", "hev1", "hvc1"]:
+        for alignment in ["au", "nal"]:
+            new_fluhwvah265dec(api, stream_format, alignment)