Set LATEST_STABLE language version and current version of stdlib to 1.3, set IS_PRE_RELEASE
Remove "EXPERIMENTAL" from 1.3 version description in tests and gradle options
The `@SinceKotlin("X.Y.Z")` annotation now hides a particular declaration from
resolution when the API version specified by the `-api-version` option is
_less_ than X.Y.Z. The comparison is performed as for versions in Maven:
MavenComparableVersion is in fact a copy of
org.apache.maven.artifact.versioning.ComparableVersion.
Also support "!API_VERSION" directive in diagnostic tests
#KT-14298 Fixed