feat(#21): saved message structure

[Bugs5382]

• initial version that will save a message if there is no proper connection to the remote site
• client/app has to return 'true' in order for the system to know the message has been saved successfully.
• client/app can use what ever tool they want to save the stringify message
• when they notice a reconnect event, they should now take their messages (from disk, etc.) and re-send them.
• The remote side should still honor their original data structure, including when the message originally was generated

[skip ci]

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Questioner

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Other things:

• Write a unit test or update unit tests that cover your change in the code?
• Set the PR to merge into the develop branch?
• Clear documentation per the guidelines in the README.md as we are support medical applications?