feat: $array indexing improvements

[phroggster]

Description of the Change

• $arrayRemove
  • Add "first" option as an index argument, with examples.
  • Shortcut single-item arrays into returning [].
• $arrayElement
  • Add numerous invocation examples.
  • Add "first" and "last" as index arguments.
  • POSSIBLY BREAKING: use Array.isArray to validate that it's an array.
    • This likely BREAKS ArrayBuffer, Uin8Array, DataView, Blob, etc. types.

Applicable Issues

N/A

Testing

Tested a command using the following in a Log Message, which all output appropriate text, g-i being null:

a) $arrayElement["[1,2,3]", 0]
b) $arrayElement["[1,2,3]", first]
c) $arrayElement["[1,2,3]", last]
d) $arrayRemove["[1,2,3]", 0]
e) $arrayRemove["[1,2,3]", first]
f) $arrayRemove["[1,2,3]", last]

g) $arrayElement["[1,2,3]", 4]
h) $arrayElement["[1,2,3]", four]
i) $arrayElement["[1,2,3]", -1]

j) $arrayRemove["[1,2,3]", 4]
k) $arrayRemove["[1,2,3]", four]
l) $arrayRemove["[1,2,3]", -1]
m) $arrayRemove["[1,2,3]", -2]

Screenshots

[phroggster]

The behavior of negative indexing in arrayElement... I'm open for suggestions. It presently returns undefined, but should probably be enhanced for reversed indexing, or similar.