Release 7.0.0 RC1

Upgrades to Traject 3

• replace map_value and first_only with Traject 3 macros
• use idiomatic Traject 3 macro syntax in MarcIndexer template

Uses a dynamic field solr schema aligned with Blacklight 7

Uses Bootstrap 4

Updates routing

• Uses routing concerns in place of v6 route set
• Removes catalog/endnote route in favor of endnote format

Updates MARC support

• Uses more appropriate styling of whitespace-sensitive MARC views
• Uses no styling of librarian view if in XHR context
• Updates shipped value mappings
• More data-resilient MARC exports

Removes unused code and fixtures