Change speed slider in Array.py

[JMCanning78]

The speed slider should be adjusted to:

• Drop the numeric display above the slider control
• Add labels for "slow" on the left and "fast" on the right
• Make the visible changes for users be about 2 seconds for slow operations and 0.05 seconds for fast operations

The idea is to have the find operation to scan all 10 cells take between 0.5 an 1.0 seconds for "fast" operation and 20 seconds for "slow" operations. Animations to remove cell values and slide over values after deletion should use the same range.

It would be good to factor the speed slider into its own module that can be reused in other visualizations. Each visualization should be able to define the range of slow to fast.