fix: handle emojis errors in delta jobs

[sbellone]

When some product attribute contain an emoji (e.g. 🐣), SFCC Delta export fails to generate a valid XML: the XML contains those characters: ��

To solve this problem, the "Filter Invalid XML Characters during Export" feature must be enabled in Administration > Global Preferences > Import & Export. When enabled, the emojis are correctly exported. (I found that thanks to this Medium post)

This PR makes to following improvements to the Delta export job:

• Report the actual error in the Business Manager. Previously we were only reporting a generic "Error reading from file..." message
  • The message also let users know about the "Filter Invalid XML Characters during Export" feature
• Move the problematic delta export files to a _failed directory. This permit to not block subsequent jobs. Currently, the file needs to be deleted manually

How to test

• Insert an emoji in a product description
• Run the delta export job
• The error should be properly reported in the logs and in the Business Manager
• The delta export files should be moved to /IMPEX/src/platform/outbox/algolia/productDeltaExport/_failed/

• Then enable the "Filter Invalid XML Characters during Export" feature
• Insert another emoji in a product description
• Run the delta export job, which should complete successfully

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SFCC-366

[htuzel]

Woow, I wasn't aware of this feature. Clear solution, thank you

[sbellone]

Note: I had forgotten to put back the lock on the master branch and merged into it.
To fix that, I've now rebased the develop branch onto master, to avoid problems during the next release.