feat: Added SentrySdk.IsSessionActive

[bitsandfoxes]

Unity SDK integrations pause and resume sessions in response to lifecycle events without knowing if a session is active. This causes repeated warnings from GlobalSessionManager ("Attempted to pause/resume a session, but a session has not been started") with no way for integrations to prevent them.

sentry-dotnet/src/Sentry/GlobalSessionManager.cs

Line 298 in fe09683

_options.LogWarning("Attempted to resume a session, but a session has not been started.");

This PR adds IHub.IsSessionActive to allow checking session state before pause/resume operations. This also gives users insights into whether there currently is a session active. I don't know how else they are supposed to deal any manual session handling anyway.

[github-actions]

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📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 2805139

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.20%. Comparing base (01d6bb8) to head (2805139).
⚠️ Report is 1 commits behind head on feat/cache-unhandled-session.

Files with missing lines	Patch %	Lines
src/Sentry/Extensibility/DisabledHub.cs	0.00%	1 Missing ⚠️
src/Sentry/Extensibility/HubAdapter.cs	0.00%	1 Missing ⚠️
src/Sentry/Internal/Hub.cs	0.00%	1 Missing ⚠️
src/Sentry/SentrySdk.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                       Coverage Diff                        @@
##           feat/cache-unhandled-session    #4662      +/-   ##
================================================================
- Coverage                         73.21%   73.20%   -0.02%     
================================================================
  Files                               479      479              
  Lines                             17370    17374       +4     
  Branches                           3431     3431              
================================================================
  Hits                              12718    12718              
- Misses                             3803     3807       +4     
  Partials                            849      849              

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[jamescrosswell]

@bitsandfoxes I'm wondering if what I'm building here might break this (and possibly other stuff):
#4664

Can Unity apps target iOS?

If so, I might need to build an IosSessionManager implementation for ISessionManager... which would be a wrapper around the CocoaSdk session manager.

Thoughts?

[jamescrosswell]

Although, I'm also guessing Session Replay isn't a thing in Unity... so maybe a non issue for this particular change.

[bitsandfoxes]

Unity targets iOS, but sessions are entirely kept and controlled on the C# side of things to keep as close to the user's code as possible. The .NET SDK already allows to pause and resume sessions, I don't see how allowing to check whether a session is active would break things.