Refactor all special case shield definitions inline

[claysmalley]

Corollary to #1074. This PR removes the special case section at the bottom of shield_defs.js, and collates all the instances of overrideByRef, overrideByName and refsByName inline with their geographically sorted definitions.

[ZeLonewolf]

Do we know why the ShieldJSON got smaller in the stats? Just want to make sure we're not losing anything in the refactor.

[claysmalley]

I changed US:NH:Turnpike to use the color constants instead of hardcoded hex values, and US:TX:Harris:HCTRA to be variable-width. Would either of those changes mess with the ShieldJSON size?

[ZeLonewolf]

I actually misspoke, the stats say the ShieldJSON is 1,484 bytes larger. That sounds like there's somehow an extra shield entry in this. I went shield by shield and couldn't find it though.

[ZeLonewolf]

I ran a script to compare the two shield json files between this PR and main, and the attached report shows the differences (in theory).
compare_report.txt

[ZeLonewolf]

On review of the comparison report, the extra size is due to bannered Georgia routes. After this consolidation, the bannered Georgia routes also gained the overrideByRef definitions for routes 515 and 520 (the blue and green routes). The prior code had the overrides get set later in the file and only on the main Georgia route networks, not the variants. Once #1073 is complete, this bit of extra duplication will go away. As such, I think this is OK to proceed with!