* Don't crash when running on Kotlin before 2.1.20+

This crash impacts people using FakeFileSystem in code
that runs in a Gradle plugin.

* Fixup FakeFileSystemTest

* Actually catch Throwable, for NoSuchMethodError

* Spotless

---------

Co-authored-by: Jesse Wilson <jwilson@squareup.com>

* Don't use Clock.System on an JVM release

Okio was broken when running on Kotlin before 2.1.20.
The failure mode was too severe - a crash at runtime!
And this is for code that worked just fine on Kotlin 2.0.x.

    java.lang.NoSuchMethodError: 'kotlin.time.Clock kotlin.internal.PlatformImplementations.getSystemClock()'
	at kotlin.time.InstantJvmKt.<clinit>(InstantJvm.kt:12)
	at kotlin.time.Clock$System.now(Clock.kt:60)
	at kotlinx.datetime.Clock$System.now(DeprecatedClock.kt:89)
	at okio.fakefilesystem.-Time.defaultClockNowMillis_delegate$lambda$2(FileMetadataCommon.kt:70)
	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
	at okio.fakefilesystem.-Time.getDefaultClockNowMillis(FileMetadataCommon.kt:65)
	at okio.fakefilesystem.FakeFileSystem.<init>(FakeFileSystem.kt:72)

The failure would occur anywhere we were running Okio's
FakeFileSystem inside a Gradle plugin.

With this change FakeFileSystem works inside a Gradle plugin,
even if the runtime Kotlin version doesn't have
kotlin.time.Clock.

* Avoid kotlinx.datetime.Clock.System.now()

* Spotless

---------

Co-authored-by: Jesse Wilson <jwilson@squareup.com>