(ref): Move SentryEventDecodable to Swift

[noahsmartin]

Moves SentryEventDecodable from objc to Swift, incremental progress to making more of the API in Swift. Also solves an SPM issue which is that Swift and objc are in different modules, and you can't add a protocol conformance across module boundaries

#skip-changelog

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.973%. Comparing base (e25f701) to head (49856f4).
Report is 11 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #5354       +/-   ##
=============================================
+ Coverage   85.966%   85.973%   +0.007%     
=============================================
  Files          394       394               
  Lines        34211     34222       +11     
  Branches     14778     14810       +32     
=============================================
+ Hits         29410     29422       +12     
+ Misses        4761      4760        -1     
  Partials        40        40               

Files with missing lines	Coverage Δ
Sources/Sentry/SentryEvent.m	99.290% <100.000%> (+0.020%)	⬆️
...es/Swift/Protocol/Codable/SentryEventCodable.swift	100.000% <ø> (ø)

... and 6 files with indirect coverage changes

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1226.73 ms	1247.72 ms	20.99 ms
Size	23.74 KiB	838.34 KiB	814.60 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
67bbc9e	1214.55 ms	1243.62 ms	29.07 ms
7b022df	1220.53 ms	1227.56 ms	7.03 ms
7bc3c0d	1212.35 ms	1228.94 ms	16.59 ms
3d8532d	1225.27 ms	1238.80 ms	13.53 ms
2a894d5	1211.02 ms	1236.72 ms	25.70 ms
b9b0f0a	1251.45 ms	1257.86 ms	6.41 ms
60bfc91	1220.39 ms	1250.89 ms	30.50 ms
eef4553	1248.12 ms	1252.37 ms	4.24 ms
add8416	1270.72 ms	1300.38 ms	29.66 ms
c48bcf6	1224.82 ms	1246.61 ms	21.80 ms

App size

Revision	Plain	With Sentry	Diff
67bbc9e	22.30 KiB	832.29 KiB	809.99 KiB
7b022df	22.85 KiB	412.95 KiB	390.10 KiB
7bc3c0d	20.76 KiB	427.35 KiB	406.59 KiB
3d8532d	22.85 KiB	414.09 KiB	391.24 KiB
2a894d5	21.58 KiB	414.57 KiB	392.99 KiB
b9b0f0a	20.76 KiB	434.94 KiB	414.18 KiB
60bfc91	20.76 KiB	434.94 KiB	414.18 KiB
eef4553	21.58 KiB	418.00 KiB	396.42 KiB
add8416	21.58 KiB	541.91 KiB	520.33 KiB
c48bcf6	22.30 KiB	823.14 KiB	800.83 KiB

Previous results on branch: convertObjcCodableSubclass

Startup times

Revision	Plain	With Sentry	Diff
9749935	1225.16 ms	1240.27 ms	15.10 ms

App size

Revision	Plain	With Sentry	Diff
9749935	23.76 KiB	838.21 KiB	814.45 KiB