add withAccents option to randUserName()

[andersonjoseph]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngneat/falso/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

randUserName() generates random user names including those with accented characters (e.g: Jiángüo.Karlsdóttir36)

What is the new behavior?

with the option: withAccents: boolean we can control if the function should generate user names with accents or not

randUserName({withAccents: false}) // Rattana.Harrison78
randUserName({withAccents: true}) // Dilóp.Háràldsdóttir93

Does this PR introduce a breaking change?

• Yes
• No