feat: added message formatters

[kyranet]

Please describe the changes this PR makes and why it should be merged:

Adds the following utilities:

• codeBlock
• inlineCode
• italic
• bold
• underscore
• strikethrough
• quote
• blockQuote
• time

ref: https://github.com/discordjs/discord.js/pull/5918

Also implemented Jest for unit testing.

Status and versioning classification:

• This PR changes the library's interface (methods or parameters added)

[codecov-commenter]

Codecov Report

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[jzeuzs]

Why is underscore and strikethrough not typed as camelCase while codeBlock and blockQuote are?

[kyranet]

Because Underscore and Strikethrough are actual words. codeBlock and blockQuote are two words joined together.