Generalize the JSON perf tests to Codable

[Catfish-Man]

No description provided.

[Catfish-Man]

@swift-ci please benchmark

[swift-ci]

Build comment file:

Build failed before running benchmark.

---

[Catfish-Man]

@swift-ci please smoke benchmark

[Catfish-Man]

@swift-ci please smoke benchmark

[swift-ci]

Build comment file:

Performance: -O

TEST	MIN	MAX	MEAN	MAX_RSS
Added
PlistPerfDecode	630	635	632	—
PlistPerfEncode	590	593	591	—

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Regression
CharacterLiteralsLarge	100	111	+11.0%	0.90x
Added
PlistPerfDecode	639	644	641	—
PlistPerfEncode	587	590	588	—

Performance: -Onone

TEST	MIN	MAX	MEAN	MAX_RSS
Added
PlistPerfDecode	708	712	710	—
PlistPerfEncode	615	620	617	—

✅	Benchmark Check Report
⚠️Ⓜ️	PlistPerfDecode has very wide range of memory used between independent, repeated measurements. PlistPerfDecode mem_pages [i1, i2]: min=[143, 151] 𝚫=8 R=[24, 0]
⚠️Ⓜ️	PlistPerfEncode has very wide range of memory used between independent, repeated measurements. PlistPerfEncode mem_pages [i1, i2]: min=[1477, 1461] 𝚫=16 R=[50, 20]

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the
regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false
alarms. Unexpected regressions which are marked with '(?)' are probably noise.
If you see regressions which you cannot explain you can try to run the
benchmarks again. If regressions still show up, please consult with the
performance team (@eeckstein).

Hardware Overview

  Model Name: Mac Pro
  Model Identifier: MacPro6,1
  Processor Name: 12-Core Intel Xeon E5
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 12
  L2 Cache (per Core): 256 KB
  L3 Cache: 30 MB
  Memory: 64 GB

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[Catfish-Man]

@swift-ci please smoke test and merge

[Catfish-Man]

@swift-ci please smoke test and merge

[Catfish-Man]

@swift-ci please smoke test and merge

[Catfish-Man]

@swift-ci please smoke test and merge

[Catfish-Man]

@swift-ci please smoke test and merge

[Catfish-Man]

@swift-ci please test and merge

[Catfish-Man]

Somehow my benchmark-only changes are causing 6 unexpected successes?

[Catfish-Man]

@swift-ci please test and merge

[Catfish-Man]

@swift-ci please test and merge

[Catfish-Man]

@swift-ci please test and merge

[Catfish-Man]

@swift-ci please test and merge

[Catfish-Man]

@swift-ci please test and merge