feat: support emoji in marble diagrams

[cartant]

Description:

This PR adds support for emoji characters in marble diagrams by leveraging ES2015's built-in emoji support for string iteration.

An attempt to add this feature was made before - in #3857 - but that attempt sought to use toArray from lodash. This PR relies upon the built-in behaviour (and downleveled iteration for the ES5 builds):

const string = '🙈🙉🙊';
const { length } = string; // 6
const characters = [...string]; // ['🙈', '🙉', '🙊']

And, let's face it, this is something that everyone wants needs, right?

Related issue (if exists): None

[benlesh]

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