Migrate practice exercises to rescript

[tejasbubane]

• [x] accumulate - #173
• [x] acronym - #174
• [x] all-your-base - #175
• [x] allergies - #179
• [x] anagram - #180
• [x] armstrong-numbers - #182
• [ ] binary-search
• [ ] bob
• [ ] change
• [x] hello-world - #172
• [ ] isogram
• [ ] leap
• [ ] minesweeper
• [ ] pangram
• [ ] phone-number
• [ ] protein-translation
• [ ] raindrops
• [ ] resistor-color
• [ ] rna-transcription
• [ ] roman-numerals
• [ ] run-length-encoding
• [ ] space-age
• [x] two-fer - #184
• [ ] word-count

[JsonKim]

@tejasbubane Hi. I made a PR #219 to migrate to ReScript. Can you review? If you review it, I will try to work on other examples as well.