ENH: handle keyType type (literal/regex) as enum instead of bool

applications/test/dictionary/Test-dictionary.C

applications/test/fvSolutionCombine/Test-fvSolutionCombine.C

applications/test/wordRe/Test-wordRe.C

src/OpenFOAM/db/dictionary/entry/entryIO.C

...hes/constraint/processorCyclic/processorCyclicPolyPatch.C

src/OpenFOAM/primitives/strings/keyType/keyType.C

src/OpenFOAM/primitives/strings/keyType/keyType.H

src/OpenFOAM/primitives/strings/keyType/keyTypeI.H

src/OpenFOAM/primitives/strings/wordRe/wordRe.H

src/OpenFOAM/primitives/strings/wordRe/wordReI.H