Add getFiatMap() method

[abhinavk99]

/v1/fiat/map is available on the free tier, as seen at https://coinmarketcap.com/api/documentation/v1/#operation/getV1FiatMap

[issue-label-bot]

Issue-Label Bot is automatically applying the label feature_request to this issue, with a confidence of 0.94. Please mark this comment with 👍 or 👎 to give our bot feedback!

Links: app homepage, dashboard and code for this bot.