Refactor: xml generation and type handling

Enhancements to XML and data type handling in astarte/tools/astarte_export

Improvements to XML generation:

astarte/tools/astarte_export/lib/xml_generate.ex:

Enhanced xml_write_full_element function to handle lists and simple values.
Added iteration through list elements to generate sub-elements dynamically.
Simplified handling for non-list values by encoding them directly.

Improvements to data type conversion:

astarte/tools/astarte_export/lib/fetchdata/fetchdata.ex:

Refactored from_native_type function for :binaryblob to use pattern matching, improving robustness and handling invalid binary values gracefully.
Added support for array types like :binaryblobarray, :booleanarray, :datetimearray, and others, leveraging Enum.map for efficient conversion.

[x] I have read CONTRIBUTING.md and CODE_OF_CONDUCT.md
[ ] I have added to CHANGELOG.md relevant changes and any other user facing change
[ ] I have added or ran the appropriate tests

What this PR does / why we need it:

The primary goal of these changes is to improve the flexibility and robustness of the XML generation and data conversion processes in the Astarte Export tool. This ensures seamless handling of various data types and structures, improving overall data export functionality.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Please review the changes in both xml_generate.ex and fetchdata.ex for alignment with existing coding standards.

Does this PR introduce a user-facing change?

[ ] Yes
[ ] No

astarte-platform / astarte