Add [[nodiscard]] attribute to native functions

[msluszniak]

Description

As in the title, add [[nodiscard]] attribute to exported functions in native implementation.

Introduces a breaking change?

• Yes
• No

Type of change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update (improves or adds clarity to existing documentation)
• Other (chores, tests, code style improvements etc.)

Tested on

• iOS
• Android

Testing instructions

Check if all demo apps work the same as previously

Screenshots

Related issues

Closes #448

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes