Add Array.length simplifications

[jfmengels]

Adds simplifications for Array.length #174

• [x] Array.length Array.empty -> 0
• [x] Array.length (Array.fromList [ a, b, c ]) -> 3
• [x] Array.length (Array.repeat 1 x) -> 1
• [x] Array.length (Array.initialize 1 f) -> 1
• [x] Array.length (Array.repeat n x) to max 0 n
• [x] Array.length (Array.initialize n f) to max 0 n

Can be reviewed commit by commit.

[jfmengels]

Thank you for the feedback and corrections! :heart: