Move implementation classes from java.lang.constant to jdk.internal.constant

[cl4es]

Move implementation classes from java.lang.constant to jdk.internal.constant, enabling a few improvements such as using a trusted factory methods from java.lang.invoke and java.lang.classfile. Intended as a follow-up to JDK-8294960-invoke.

Bootstrap improves from around ~693k bytecode executed to ~670k on HelloLambda. A few targetted microbenchmarks see improvements, in particular MethodTypeDescFactories.ofDescriptor:

Name                                                             (descString) Cnt     Base     Error      Test    Error  Unit  Change
MethodTypeDescFactories.ofDescriptor  (Ljava/lang/Object;Ljava/lang/String;)I   6  138,040 ±   0,728   135,811 ±  6,182 ns/op   1,02x (p = 0,056 )
MethodTypeDescFactories.ofDescriptor                                      ()V   6   12,422 ±   5,208    11,371 ±  0,202 ns/op   1,09x (p = 0,224 )
MethodTypeDescFactories.ofDescriptor ([IJLjava/lang/String;Z)Ljava/util/List;   6  200,177 ±   4,324   177,817 ± 25,360 ns/op   1,13x (p = 0,002*)
MethodTypeDescFactories.ofDescriptor                    ()[Ljava/lang/String;   6   60,531 ±   3,007    28,605 ±  8,503 ns/op   2,12x (p = 0,000*)
MethodTypeDescFactories.ofDescriptor                                 (..IIJ)V   6  279,014 ±  10,316   202,877 ±  4,435 ns/op   1,38x (p = 0,000*)
MethodTypeDescFactories.ofDescriptor                 (.....................).   6 2224,271 ± 121,582  1312,268 ± 61,346 ns/op   1,69x (p = 0,000*)
  * = significant