Add iOS IMO HD chat message custom parser plugin

[agusgiinarsa]

One line description of pull request

Add iOS IMO HD chat message custom parser plugin

Description:

In this pull request I add several files :
• Add file plaso/parsers/sqlite_plugins/ios_imohdchat_message.py
• Add one line at plaso/parsers/sqlite_plugins/init.py
• Add file plaso/tests/parsers/sqlite_plugins/ios_imohdchat_message.py
• Add file plaso/test_data/IMODb2.sqlite to use as test data (from iOS forensic image in Digital Corpora)

Related issue (if applicable): fixes #

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Checklist:

• Automated checks (GitHub Actions, AppVeyor) pass
• No new new dependencies are required or l2tdevtools has been updated
• Reviewer assigned