utils: add --time-tests to lit invocation

[compnerd]

Try to extract more timing information about the tests to understand CI times better.

[compnerd]

@swift-ci please smoke test

[compnerd]

@swift-ci please smoke test Linux platform

[compnerd]

@swift-ci please smoke test Linux platform

[compnerd]

Interesting information from the new flags:

Slowest Tests:
--------------------------------------------------------------------------
1117.96s: Swift(windows-x86_64) :: Misc/stats_dir_profiler.swift
347.24s: Swift(windows-x86_64) :: Misc/verify-swift-feature-testing.test-sh
161.87s: Swift(windows-x86_64) :: InterfaceHash/edited_property_getter.swift
161.49s: Swift(windows-x86_64) :: InterfaceHash/edited_method_body.swift
93.77s: Swift(windows-x86_64) :: Generics/rdar74321043.swift
69.62s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/foundation-and-std-module.swift
60.24s: Swift(windows-x86_64) :: Interpreter/dynamic_replacement.swift
52.82s: Swift(windows-x86_64) :: refactoring/ConvertAsync/basic.swift
50.41s: Swift(windows-x86_64) :: Interop/CxxToSwiftToCxx/span/span-execution.cpp
45.44s: Swift(windows-x86_64) :: Driver/response-file.swift
45.37s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-string.swift
44.04s: Swift(windows-x86_64) :: Casting/TypeOf_ExtendedExistential.swift
42.21s: Swift(windows-x86_64) :: Index/index_swift_only_systemmodule.swift
41.98s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-pair.swift
40.75s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-chrono.swift
40.21s: Swift(windows-x86_64) :: Interop/Cxx/class/copy-move-assignment-executable.swift
40.03s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-function.swift
39.33s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-string-view.swift
37.39s: Swift(windows-x86_64) :: Interop/Cxx/stdlib/use-std-string-with-opts.swift
34.51s: Swift(windows-x86_64) :: Interop/Cxx/class/move-only/move-only-cxx-value-type.swift

Tests Times:
--------------------------------------------------------------------------
[    Range    ] :: [               Percentage               ] :: [   Count   ]
--------------------------------------------------------------------------
[1100s,1200s) :: [                                        ] :: [    1/11305]
[1000s,1100s) :: [                                        ] :: [    0/11305]
[ 900s,1000s) :: [                                        ] :: [    0/11305]
[ 800s, 900s) :: [                                        ] :: [    0/11305]
[ 700s, 800s) :: [                                        ] :: [    0/11305]
[ 600s, 700s) :: [                                        ] :: [    0/11305]
[ 500s, 600s) :: [                                        ] :: [    0/11305]
[ 400s, 500s) :: [                                        ] :: [    0/11305]
[ 300s, 400s) :: [                                        ] :: [    1/11305]
[ 200s, 300s) :: [                                        ] :: [    0/11305]
[ 100s, 200s) :: [                                        ] :: [    3/11305]
[   0s, 100s) :: [*************************************** ] :: [11300/11305]
--------------------------------------------------------------------------