PG-2240 Add pg_upgrade support for encrypted tables

[jeltz]

To safely run pg_upgrade with SMGR encryption enabled people need to first copy the data directory and then we have changed pg_tde so that it no longer overwrites or deletes keys when ran in binary upgrade mode.

Encrypted WAL is still not supported in pg_upgrade and it may also make sense to write a script which automates copying the pg_tde directory.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.14%. Comparing base (f9d8a53) to head (73fae64).
⚠️ Report is 1 commits behind head on main.

❌ Your project status has failed because the head coverage (60.14%) is below the target coverage (90.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #522      +/-   ##
==========================================
+ Coverage   60.06%   60.14%   +0.08%     
==========================================
  Files          68       68              
  Lines       10677    10680       +3     
  Branches     1835     1837       +2     
==========================================
+ Hits         6413     6424      +11     
+ Misses       3557     3552       -5     
+ Partials      707      704       -3     

Components	Coverage Δ
access	84.49% <ø> (+0.34%)	⬆️
catalog	87.93% <ø> (ø)
common	77.77% <ø> (ø)
encryption	73.94% <ø> (ø)
keyring	74.28% <ø> (ø)
src	93.23% <ø> (ø)
smgr	94.14% <100.00%> (+0.08%)	⬆️
transam	∅ <ø> (∅)

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[AndersAstrand]

Looks like #include <miscadmin.h> needs to be moved outside the #if PG_VERSION_NUM >= 180000 for this to work with 17.

Also the commit message is a little hard to read. Which "data directory" needs to be copied? I think the actual behavior change here needs to be presented first, and then we can talk about the added test and why the pg_tde/ directory (not the data directory) needs to be copied in it.

I don't think we should make assertions on the "cp" command, it should be assumed to work imho.