Fix ImageFileReader error message & add back otb::Logger::BuildFormattedEntry

Summary

• Fix unclear error message in ImageFileReader (see discussion in #1850 (closed))
• Add back otb::Logger::BuildFormattedEntry override (removed in !379 (merged))

Rationale

• Fix issue #1850 (closed)
• Better format for log entries (no redundant spaces and don't show logger name)

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 👍 votes from core developers, no 👎 vote.
• The feature branch is (reasonably) up-to-date with the base branch
• Dashboard is green
• Copyright owner has signed the ORFEO ToolBox Contributor License Agreement