Rename and consolidate tests in future-reserved-words directory

test/language/future-reserved-words/7.6.1.2-1-s.js

test/language/future-reserved-words/7.6.1.2-3-s.js

test/language/future-reserved-words/7.6.1.2-4-s.js

test/language/future-reserved-words/7.6.1.2-6-s.js

test/language/future-reserved-words/7.6.1.2-7-s.js

test/language/future-reserved-words/7.6.1.2-8-s.js

test/language/future-reserved-words/7.6.1.2-9-s.js

test/language/future-reserved-words/S7.6.1.2_A1.15.js

test/language/future-reserved-words/S7.6.1.2_A1.18.js

test/language/future-reserved-words/S7.6.1.2_A1.21.js

test/language/future-reserved-words/S7.6.1.2_A1.22.js

test/language/future-reserved-words/S7.6.1.2_A1.23.js

test/language/future-reserved-words/S7.6.1.2_A1.24.js

test/language/future-reserved-words/S7.6.1.2_A1.26.js

test/language/future-reserved-words/_implements.js

test/language/future-reserved-words/abstract.js

test/language/future-reserved-words/boolean.js

test/language/future-reserved-words/byte.js

test/language/future-reserved-words/char.js

test/language/future-reserved-words/class.js