* fix cabal install --program-suffix/prefix (fix #10290 and #10476)

When checking for existing installations, cabal would not account for
an affix (suffix or prefix). So, if you had a `hello` binary installed, installing a
second one with a non-empty affix (a perfectly legal operation) would
fail.

The reason seemed to be a typo in
09c04e9a, which passed the arguments to
the Symlink structure in a wrong order.

When failing to install a binary because of an existing one, cabal would
report suffix-less existing target even if a suffix was set.

* Add regression tests for overwrite policies and porgram-affixes

Add regression tests for the `program-prefix` and `program-suffix` flags
combined with the overwrite-policy.
In short, the overwrite-policy needs to take potential program affixes
into account when deciding whether it will need to overwrite a program
path during installation.

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Co-authored-by: Fendor <fendor@posteo.de>