CLI - export failures are not properly logged and reported

[mreynolds389]

When a "Can't open file" type of error occurs, db2ldif command line does not display the error.
Seeing the ldiffile path displayed is misleading and makes think that the file as actually been created.
Nothing shows that the operation couldn't be performed, unless looking at the errors log

Version-Release number of selected component (if applicable):
389-ds-base-1.4.3.8-4.module+el8.3.0+7193+dfd1e8ad.x86_64

How reproducible:
always

Steps to Reproduce:
automated test export/export_test.py::test_db2ldif_with_non_accessible_ldif_file_path will be sent soon as PR for review
or

1. import data in "dc=example,dc=com"
2. stop the ds instance
3. run # db2ldif -Z standalone1 -s "dc=example,dc=com" -a ldif/db.ldif

Actual results:

db2ldif -Z standalone1 -s "dc=example,dc=com" -a ldif/db.ldif
Exported ldif file: /mnt/tests/rhds/tests/upstream/ldif/db.ldif
[24/Jul/2020:04:55:06.947184501 -0400] - INFO - slapd_exemode_db2ldif - db2ldif - Backend Instance(s):
[24/Jul/2020:04:55:06.952243624 -0400] - INFO - slapd_exemode_db2ldif - db2ldif - userRoot
ldiffile: /mnt/tests/rhds/tests/upstream/ldif/db.ldif

Expected results:

The error should be displayed as command output, in addition of info already displayed :
[24/Jul/2020:04:55:06.976484643 -0400] - ERR - bdb_db2ldif - db2ldif: userRoot: can't open /mnt/tests/rhds/tests/upstream/ldif/db.ldif: 2 (No such file or directory) while running as user "dirsrv"

It should be clear that ldiffile: /mnt/tests/rhds/tests/upstream/ldif/db.ldif couldn't be created and that the operation failed

---

This original bug was for the old perl scripts, but dsctl/dsconf still have the same type of problems.

https://bugzilla.redhat.com/show_bug.cgi?id=1860291

[mreynolds389]

944202f..9caf8a1 389-ds-base-2.2 -> 389-ds-base-2.2
f78614b..0c894c6 389-ds-base-2.1 -> 389-ds-base-2.1
0a77fae..c19148b 389-ds-base-2.0 -> 389-ds-base-2.0
00f42cf..f8dc05e 389-ds-base-1.4.3 -> 389-ds-base-1.4.3