entry: Enable context menu with mosue down even if the entry is not editable in some...

entry: Enable context menu with mosue down even if the entry is not editable in some case.

Summary:
Even if a entry is not editable, user can select text in the entry.
When the entry has selection, we have to support "copy" option.
@fix

Test Plan:
Precondition: Apply D852 patch for fixing a bug in elementary_test
1. elementary_test -to entry7
2. Select some text in the non-editable entry.
3. Press mouse right button.

Note: You can test it in Desktop profile.

Reviewers: tasn, woohyun, seoz

Differential Revision: https://phab.enlightenment.org/D848