Add "features" tag to test templates

src/dstr-binding/default/arrow-function.template

src/dstr-binding/default/cls-decl-gen-meth-static.template

src/dstr-binding/default/cls-decl-gen-meth.template

src/dstr-binding/default/cls-decl-meth-static.template

src/dstr-binding/default/cls-decl-meth.template

src/dstr-binding/default/cls-expr-gen-meth-static.template

src/dstr-binding/default/cls-expr-gen-meth.template

src/dstr-binding/default/cls-expr-meth-static.template

src/dstr-binding/default/cls-expr-meth.template

src/dstr-binding/default/const-stmt.template

src/dstr-binding/default/func-decl.template

src/dstr-binding/default/func-expr.template

src/dstr-binding/default/gen-func-decl.template

src/dstr-binding/default/gen-func-expr.template

src/dstr-binding/default/gen-meth.template

src/dstr-binding/default/let-stmt.template

src/dstr-binding/default/meth.template

src/dstr-binding/default/var-stmt.template