Draft: Add settings to extension

This is my first contribution, so if i've missed anything, sorry in advance! I've selected to not squash commits when this PR merges.

This PR adds settings for Surfer within VS Code's Settings area, which get applied as defaults to newly opened files:

• time unit
• variable alignment
• clock highlighting
• hierarchy / side panel layout
• arrow key behavior
• default variable filter type
• default variable name type
• time format

I've skipped the following settings, since it doesn't appear that we have setters, just toggle, so if we added defaults for these, we'd have to either hardcode the defaults for that version, or introduce getters, so we can send the right setting values to Surfer:

• show tick lines
• show variable tooltip
• show scope tooltip
• show variable indicies
• show variable direction
• show empty scopes
• show parameters in scopes