This applies the fix from #1821 to the remaining frontmatter properties that consist of lists.

Ref. https://github.com/tc39/test262/pull/1821/files#r222811633.
Ref. #1817.

In order to promote readability of the generated test material, the test
generation tool may insert whitespace if the context a given expanded
variable calls for it. Avoid inserting such whitespace within literal
values that span multiple lines.

Extend the test generation tool to emit the recently-modified format of
the "negative" meta-data. Update the effected test case files
accordingly.

When inspecting previously-generated files, a new `Test` instance should
be used. This avoids over-writing the in-memory representation of the
latest test, and allows previously-existing test files to be partially
updated according to subsequent changes in their respective source/case
files.

In expecting "case directories" to contain a sub-directory named
"default", the test generation tool is unable to generate tests for
features where a directory named "default" is not appropriate.

Modify the heuristic that identifies "case directories" to use a more
fundamental aspect (i.e. the existence of at least one "case" file).

Extend test generation tool to recognize and expand interpolation
patterns within string literals.