[benchmark] Add benchmark for generic floating-point to integer conversion

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This PR adds another benchmark, this time for generic floating-point to integer conversion, in anticipation of assessing the fast path to be added in #33889.

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@swift-ci test

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@swift-ci benchmark

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@swift-ci benchmark

[swift-ci]

Performance: -O

Regression	OLD	NEW	DELTA	RATIO
Dictionary4	150	195	+30.0%	0.77x
Dictionary4OfObjects	187	230	+23.0%	0.81x
Improvement	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStubToNSStringRef	76	68	-10.5%	1.12x (?)
Added	MIN	MAX	MEAN	MAX_RSS
ConvertFloatingPoint.MockFloat64ToInt64	563	570	566	—

Code size: -O

Regression	OLD	NEW	DELTA	RATIO
FloatingPointConversion.o	25608	27007	+5.5%	0.95x

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
CharacterLiteralsLarge	63	71	+12.7%	0.89x
Set.subtracting.Empty.Box	8	9	+12.5%	0.89x (?)
ArrayAppendUTF16Substring	31464	34020	+8.1%	0.92x (?)
DictionaryBridgeToObjC_BulkAccess	102	110	+7.8%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
ConvertFloatingPoint.MockFloat64ToDouble	16	14	-12.5%	1.14x (?)
Added	MIN	MAX	MEAN	MAX_RSS
ConvertFloatingPoint.MockFloat64ToInt64	603	628	615	—

Code size: -Osize

Regression	OLD	NEW	DELTA	RATIO
FloatingPointConversion.o	24236	25738	+6.2%	0.94x

Performance: -Onone

Added	MIN	MAX	MEAN	MAX_RSS
ConvertFloatingPoint.MockFloat64ToInt64	52484	52559	52518	—

Code size: -swiftlibs

✅	Benchmark Check Report
⚠️🔤	ConvertFloatingPoint.MockFloat64ToInt64 name is composed of 5 words. Split ConvertFloatingPoint.MockFloat64ToInt64 name into dot-separated groups and variants. See http://bit.ly/BenchmarkNaming

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 mini
  Model Identifier: Macmini8,1
  Processor Name: 6-Core Intel Core i7
  Processor Speed: 3.2 GHz
  Number of Processors: 1
  Total Number of Cores: 6
  L2 Cache (per Core): 256 KB
  L3 Cache: 12 MB
  Memory: 64 GB

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@swift-ci test macOS platform

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@swift-ci test Linux platform