BUG: Add deprecated EncodedStreamObject functions back until PyPDF2==…

…3.0.0 (#1139)

Accidentally, PyPDF2 did not follow the deprecation process:
https://pypdf2.readthedocs.io/en/latest/dev/deprecations.html

ISSUE: The EncodedStreamObject.getData / setData were removed
AFFECTS: PyPDF2>=1.28.3,<=2.6.0
FIX: Add the getData / setData methods back with deprecation warnings

Closes #1138

PyPDF2/generic.py

@@ -1162,9 +1162,17 @@ def get_data(self) -> Union[None, str, bytes]:
             self.decoded_self = decoded
             return decoded._data
 
+    def getData(self) -> Union[None, str, bytes]:  # pragma: no cover
+        deprecate_with_replacement("getData", "get_data")
+        return self.get_data()
+
     def set_data(self, data: Any) -> None:
         raise PdfReadError("Creating EncodedStreamObject is not currently supported")
 
+    def setData(self, data: Any) -> None:  # pragma: no cover
+        deprecate_with_replacement("setData", "set_data")
+        return self.set_data(data)
+
 
 class ContentStream(DecodedStreamObject):
     def __init__(