Add primative testcases for new Builder documentation

Have made 13 sets of test cases to begin the process of adding further groovy-core documentation for the Builder series of tools. All test sets are very basic. Have loaded compiled and tested the full groovy-core on my local system. These 13 tests fail and succeed where i expected. Next expect to develop companion .ADOC documentation files that uses these tests for each builder.

longer term would want to evolve more detailed test cases for each builder with matching documentation.

These changes require the creation of several folders so that groovy-core/src/spec  groovy-core/src/spec/doc groovy-core/src/spec/test folders are also matched in subprojects too.