Improve error messages with helpful hints and solutions

[zarch]

As a new atac user, I encountered difficulties understanding why certain API requests were failing. This PR improves error messages to guide users in identifying issues and finding solutions.

Changes

• Add format_error_message() function to analyze reqwest errors;
• Detect TLS certificate errors and suggest --accept-invalid-certs flag;
• Detect hostname mismatches and suggest --accept-invalid-hostnames flag;
• Provide specific suggestions for timeout, connection, and redirect errors;
• Include contextual hints for most error types.

Before vs After

Before:

error sending request for url (https://example.com/api)

After:

error sending request for url (https://example.com/api)

💡 TLS Certificate Error: The server is using a self-signed or untrusted certificate.
   Solution: Use --accept-invalid-certs flag or enable 'Accept invalid certs' in TUI settings

[Julien-cpsn]

Hello,

Just to let you know, I started reviewing and working on your PR.

Have a great day