ENH: add stringOps namespace with a collection of string-related ops

src/OpenFOAM/Make/files

...OAM/db/dictionary/functionEntries/codeStream/codeStream.C

...OAM/db/dictionary/functionEntries/codeStream/codeStream.H

...b/dictionary/functionEntries/codeStream/codeStreamTools.C

...b/dictionary/functionEntries/codeStream/codeStreamTools.H

src/OpenFOAM/primitives/strings/string/string.C

src/OpenFOAM/primitives/strings/stringOps/stringOps.C

src/OpenFOAM/primitives/strings/stringOps/stringOps.H