feat: enable hashid alphabet + hashMinLength to be configured

[oddnavy]

We needed to adjust the hashid config when working on a project. This PR adds the ability to change the hashid alphabet and min hash length

[rungta]

Thank you for the pull request @oddnavy! It’ll be great if you can make the following minor edits:

• Let the default alphabet config value be null
• Only pass a third argument to the Hashids() constructor if we have a non-null $this->alphabet value
• Undo whitespace changes

[oddnavy]

No worries @rungta. I've pushed some changes.

Only pass a third argument to the Hashids() constructor if we have a non-null $this->alphabet value

How would recommend doing ☝️