feat: Remove SentryOptions.enabled

[philipphofmann]

📜 Description

Other SentrySDKs don't have this option. We want to align with them and remove it.
Furthermore, SentryClient now doesn't send any events or sessions if the DSN is nil.

💡 Motivation and Context

Other SentrySDKs don't have this option. We want to align with them and remove it.

💚 How did you test it?

Travis.

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the CHANGELOG
• No breaking changes

🔮 Next steps

[codecov-commenter]

Codecov Report

Merging #736 into master will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #736      +/-   ##
==========================================
+ Coverage   91.92%   92.06%   +0.13%     
==========================================
  Files          71       71              
  Lines        3071     3061      -10     
==========================================
- Hits         2823     2818       -5     
+ Misses        248      243       -5     

Impacted Files	Coverage Δ
Sources/Sentry/SentryClient.m	91.42% <100.00%> (+0.12%)	⬆️
Sources/Sentry/SentryOptions.m	100.00% <100.00%> (ø)
Sources/Sentry/SentryThreadInspector.m	100.00% <0.00%> (+3.57%)	⬆️
Sources/Sentry/SentrySDK.m	61.44% <0.00%> (+4.81%)	⬆️

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[bruno-garcia]

Nice! deleted code replaced with testing the correct behavior!

[eric]

This is really a bummer. We relied on this to easily enable/disable sending to Sentry based on user privacy settings. It doesn't appear that there is any other mechanism we can use at runtime to enable and disable sending to Sentry.

[philipphofmann]

@eric someone already opened up a PR for this #700, but didn't continue with our feedback. Maybe we just grab it ourselves and finish it. You are also welcome to help us out on this one.

[lhunath]

@philipphofmann It should be noted that #700 cannot (in its current form) be used for toggling the state of Sentry based on the user's privacy preferences / consent, since it's read-only.

[eric]

Honestly the feature we’re looking for is exactly what this feature did. We need something we can toggle at runtime. If I were to propose a new feature, it would be just reverting this pull request.

[lhunath]

I understand there's a rational for homogenizing the different platform SDKs, but in doing so has Sentry considered the impact that the solution of removing enabled has on the use case of consent management or was this effect not considered as part of this decision? If yes, I'd be keen to hear what the conclusion was and whether there's an alternative suggestion for handling consent. If no, I recommend that Sentry both consider consent management now and also adopts a more conscientious strategy to modifying existing API.

[philipphofmann]

@eric and @lhunath thanks a lot for your input. I opened up an issue for this. Let's move the discussion there please: #809