Replace Zend_Db_Table_Rowset docblocks with generics to allow better type hinting

[tomasfejfar]

This is a PoC, that's still somewhat limited due to phpstan/phpstan#5817 but I got the rest working in tomasfejfar/phpstan-zf1#2.

Do you like the way this is heading? I wonder if this is the right way and wanted to get some feedback early.

[codecov]

Codecov Report

Merging #116 (460f49f) into master (17293b7) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #116   +/-   ##
=========================================
  Coverage     55.26%   55.26%           
  Complexity     1722     1722           
=========================================
  Files            42       42           
  Lines          4706     4706           
=========================================
  Hits           2601     2601           
  Misses         2105     2105           

Impacted Files	Coverage Δ
src/Zend/Db/Table/Rowset/Abstract.php	97.87% <ø> (ø)

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[jaydiablo]

@tomasfejfar we actually don't use the Zend_Db component in our apps, so I don't think I'm the best person to get feedback from on this :)

I'm open to merging changes once you're happy with it though.