Fix context to native sync for sentry context types

[denrase]

📜 Description

Fixes an issue where we'd call toString() on sentry context types when synging to native. This in turn broke load contexts integration, as a map was expected, and instead it was the toString() string.

💡 Motivation and Context

Fixes #3006

💚 How did you test it?

Unit tests. Ran on sample app.

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• No new PII added or SDK only sends newly added PII if sendDefaultPii is enabled
• I updated the docs if needed
• All tests passing
• No breaking changes

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 87.73%. Comparing base (33f99c9) to head (edbb282).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
flutter/lib/src/native/native_scope_observer.dart	71.42%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3012      +/-   ##
==========================================
- Coverage   87.74%   87.73%   -0.02%     
==========================================
  Files         286      286              
  Lines        9335     9340       +5     
==========================================
+ Hits         8191     8194       +3     
- Misses       1144     1146       +2     

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[github-actions]

iOS Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1258.85 ms	1271.16 ms	12.31 ms
Size	7.86 MiB	9.45 MiB	1.59 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
c1bb00f	1265.14 ms	1290.85 ms	25.71 ms
f172c4d	1350.66 ms	1408.49 ms	57.83 ms
0be962b	1264.10 ms	1281.16 ms	17.06 ms
6325c3b	1266.52 ms	1291.06 ms	24.54 ms
e1897c5	1252.61 ms	1276.48 ms	23.87 ms
aa950e9	1275.17 ms	1295.33 ms	20.16 ms
a49594a	1284.83 ms	1313.29 ms	28.45 ms
1131914	1277.20 ms	1300.20 ms	23.00 ms
7659cbe	1246.70 ms	1265.88 ms	19.17 ms
3f23617	1261.93 ms	1286.10 ms	24.17 ms

App size

Revision	Plain	With Sentry	Diff
c1bb00f	8.09 MiB	9.07 MiB	1001.06 KiB
f172c4d	8.33 MiB	9.62 MiB	1.29 MiB
0be962b	8.10 MiB	9.16 MiB	1.07 MiB
6325c3b	8.16 MiB	9.17 MiB	1.01 MiB
e1897c5	8.42 MiB	9.91 MiB	1.49 MiB
aa950e9	8.16 MiB	9.17 MiB	1.01 MiB
a49594a	8.16 MiB	9.16 MiB	1.00 MiB
1131914	8.16 MiB	9.17 MiB	1.01 MiB
7659cbe	8.42 MiB	9.89 MiB	1.47 MiB
3f23617	8.16 MiB	9.17 MiB	1.01 MiB

Previous results on branch: fix/feature-flags-breaks-context

Startup times

Revision	Plain	With Sentry	Diff
2d8e518	1255.83 ms	1271.89 ms	16.06 ms

App size

Revision	Plain	With Sentry	Diff
2d8e518	7.85 MiB	9.45 MiB	1.59 MiB

[github-actions]

Android Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	569.54 ms	591.00 ms	21.46 ms
Size	6.54 MiB	7.53 MiB	1017.40 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
8ced2dc	295.58 ms	336.49 ms	40.91 ms
4b29d6e	386.80 ms	430.86 ms	44.06 ms
5f443de	412.30 ms	491.67 ms	79.37 ms
04db237	330.16 ms	428.38 ms	98.22 ms
689d2fd	378.62 ms	430.48 ms	51.86 ms
6572f8d	302.35 ms	348.10 ms	45.75 ms
ccc09e4	308.21 ms	357.74 ms	49.54 ms
7954fb3	459.38 ms	500.72 ms	41.34 ms
33f99c9	668.33 ms	735.08 ms	66.76 ms
dd5521e	454.51 ms	538.29 ms	83.78 ms

App size

Revision	Plain	With Sentry	Diff
8ced2dc	6.06 MiB	7.03 MiB	990.29 KiB
4b29d6e	6.33 MiB	7.26 MiB	946.14 KiB
5f443de	6.35 MiB	7.34 MiB	1008.00 KiB
04db237	5.94 MiB	6.95 MiB	1.01 MiB
689d2fd	6.06 MiB	7.10 MiB	1.04 MiB
6572f8d	6.15 MiB	7.13 MiB	999.97 KiB
ccc09e4	5.94 MiB	6.95 MiB	1.01 MiB
7954fb3	6.49 MiB	7.57 MiB	1.08 MiB
33f99c9	6.54 MiB	7.53 MiB	1017.45 KiB
dd5521e	6.44 MiB	7.50 MiB	1.06 MiB

Previous results on branch: fix/feature-flags-breaks-context

Startup times

Revision	Plain	With Sentry	Diff
2d8e518	462.04 ms	473.65 ms	11.60 ms

App size

Revision	Plain	With Sentry	Diff
2d8e518	6.54 MiB	7.53 MiB	1017.82 KiB

[buenaflor]

lgtm 👍