BUG: Add missing deprecated EncodedStreamObject functions

[MasterOdin]

Closes #1138

The EncodedStreamObject class was missing the deprecated getData and setData functions, which would call the get_data and set_data functions respectively after issuing a deprecation warning. The original functions were totally renamed in c774ab0. That same commit did properly handle the getData and setData functions in the DecodedStreamObject though, where they issue a deprecation warning and then call get_data and set_data.

This should probably be backported to 1.x where it exists as well, as it should be simple enough, and the user in #1138 is using 1.28.2 and cannot upgrade due to this bug.

[codecov]

Codecov Report

Merging #1139 (4a1304f) into main (fd00f20) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1139   +/-   ##
=======================================
  Coverage   91.94%   91.94%           
=======================================
  Files          24       24           
  Lines        4681     4681           
  Branches      967      967           
=======================================
  Hits         4304     4304           
  Misses        231      231           
  Partials      146      146           

Impacted Files	Coverage Δ
PyPDF2/generic.py	91.72% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fd00f20...4a1304f. Read the comment docs.

[MartinThoma]

Thank you 🤗 I will make a release today with the fix for the current main branch.

I'm uncertain if I really want to do backports. For which versions would I need to do them? For which kinds of bugs would we make it? How long would we need to support old versions?

[MasterOdin]

I think the only thing that should be backported is just these sorts of PRs, where functions were unintentionally broken by a rename or whatever, and that the fix is super straightforward. Given the probably very long tail of 1.x usage that exists and time between major releases, I would say support backporting for like 6 months or so, but I don't imagine there should be that many of these sorts of reports.

Any other changes or features I think should not be backported.

[MartinThoma]

Sounds good and also a reasonable workload. Let's do that :-) Thank you :-)