Fix missing encoding attribute on FN field.

When FN field is built from display name, the encoding attribute is missing.
Created common method to build N and FN fields so they will not be out of
sync in the future.

Bug: 7292017
Change-Id: I7faceb316b639d626a54bdd455df1e748b22face
Allow importer to handle missing encoding attribute for FN.

- Removed separators from FN properties.
- Adding fix on importer side since we cannot fix exporters that already exist.

Bug: 7292017
Change-Id: I61c691c24828e63aac1920384e16461da7a03881
Store encoding in upper case.

Instead of checking for up case each time or using equalsIgnoreCase.

Bug: 7292017
Change-Id: I3954a2e0fdb757d157bcf3dff77ed2749a9577d8