Feature/dynamic attachment support

[BartoszLitwiniuk]

Overview

This PR adds support for dynamic attachments for Backtrace Android SDK. With this change, clients can attach arbitrary assets e.g. files, logs, screenshots to error or crash reports at runtime providing path to certain file. Attachments can be added after BacktraceClient initialization.

Changes

• Introduced APIs that let users supply attachments by providing paths after BacktraceClient initialization.
• Added unit tests covering scenarios with providing attachments in different ways (client initialization, post client initialization, during report send)

Backward Compatibility

• Existing usage (sending error/crash reports without attachments) remains fully unchanged: if users don’t supply attachments, reports behave exactly as before.
• The new attachment APIs are optional and additive — they don’t break or alter existing workflows.

Motivation

• Richer context: allowing attachments like logs, configuration files, or screenshots can dramatically improve the ability to diagnose issues, especially those that are hard to reproduce.
• Parity across platforms: other clients / SDKs (on different platforms) already support dynamic attachments so this brings Android up to the same level of functionality.
• Developer convenience: rather than forcing clients to manage external file uploads separately, this built-in support makes it much easier to include extra diagnostics directly with each report — reducing friction and encouraging better bug reports.

Note

This PR will follow to update the client documentation accordingly.