Modernize pre-C++11 copy prevention to = delete across core/ and protocols/ (#700)
## Summary
Replace the pre-C++11 idiom (declared-but-undefined private copy ctor /
copy assignment used to prevent copies via link error) with explicit `=
delete`. 16 files, no behaviour change — just turning latent link errors
into clear compile-time errors. Same kind of work as #685 / #674 / #672
/ #671 / etc.
Two flavours:
1. **Stand-alone non-copyable classes** (14 files): replace the
unimplemented private declarations with `= delete`. Drops redundant
comments (`"deny use of the copy constructor"`, `"private and
unimplemented"`) that `= delete` already conveys. Keeps the explanatory
rationale only where the *why* is non-obvious (`ScoreFunction` /
`DockingScoreFunction` / `OtherContextScoreFunction`: copies would
discard subclass information; use `clone()` instead).
2. **Singleton** (`SymDofMoverSampler`, inheriting
`utility::SingletonBase`): drop the redundant copy/assignment
declarations entirely — the base already `= delete`s its own copies,
which transitively deletes the derived copies.
### Files touched
`core/scoring/`: `ScoreFunction.hh`, `MinScoreScoreFunction.hh`,
`DockingScoreFunction.hh`
`core/pack/rotamer_set/`: `RotamerSet.hh`, `RotamerSet_.hh`,
`RotamerSubset.hh`
`core/conformation/`: `RotamerSetBase.hh`
`core/environment/`: `DofPassport.hh`
`core/fragment/`: `ConstantLengthFragSetIterator_.hh`,
`FrameListIterator_.hh`, `MinimalFragSetIterator_.hh`,
`OrderedFragSetIterator_.hh`
`basic/resource_manager/locator/`: `FileSystemResourceLocator.hh` (the
inner `FileStream`)
`protocols/flexpack/`: `OtherContextScoreFunction.hh`
`protocols/frag_picker/`: `FragmentPicker.hh` (the inner `QuotaDebug`)
`protocols/matdes/`: `SymDofMoverSampler.hh`