Issue #2891935 by maxocub, Jo Fitzgerald, heddn: Refactor D7 FieldInstance source plugin and other field instance related source plugins

(cherry picked from commit 4ff7617a)

Issue #2845486 by Jo Fitzgerald, quietone, gaurav.kapoor, ohthehugemanatee, heddn, Yogesh Pawar, catch, shabana.navas, phenaproxima, mikeryan: Rename Migration process plugin and add documentation

Issue #2611066 by hussainweb, svendecabooter, brunodbo, generalredneck, iMiksu, joelpittet: Migration path to entity reference field from 7.x

Revert "Issue #2683435 by hussainweb, mikeryan, quietone, alexpott, michael_wojcik, phenaproxima, benjy: Consider renaming Migrate's cckfield plugins"

This reverts commit 24f816a1.

Issue #2683435 by hussainweb, mikeryan, quietone, alexpott, michael_wojcik, phenaproxima, benjy: Consider renaming Migrate's cckfield plugins

Revert "Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal"

This reverts commit 89815ba3.

Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal

Issue #2631736 by quietone, jmuzz, Sam152, svendecabooter, benjy: Cckfield Plugins must distinguish core versions

Issue #2416765 by phenaproxima, miguelc303, hussainweb, mikeryan, benjy, chx: Migrate Drupal 7 Field/Instance/View mode settings

Issue #2534010 by phenaproxima, mikeryan: Move module-specific migration support into the field module

Issue #2463909 by phenaproxima, mikeryan: Migrations should support non-installed default configurations (templates)

Issue #2509496 by chx, benjy, phenaproxima: Make migrate process plugins more flexible/less boilerplate

Issue #2460529 by alexpott, chx, phenaproxima: Migrations need to use the configuration entity dependency system

Issue #2466797 by mikeryan, benjy: Rename migration_groups key to avoid confusion with MigrationGroup support

Issue #2448501 by ultimike, phenaproxima, benjy: Use the migrate cckfield plugin type for the link field

Issue #2271419 by alexpott, larowlan: Fixed Allow field types, widgets, formatters to specify config dependencies.

Issue #2293773 by Gábor Hojtsy, alexpott, penyaskito: Fixed migrations use dots in key names - not allowed in config.

Issue #2005434 by alexpott, heddn, andrewmacpherson, swentel: Let 3rd party modules store extra configuration in EntityDisplay.

Issue #2121299 by andypost, bdone, benjy, penyaskito, chx, claudiu.cristea, damiankloip, gregboggs, InternetDevels, jessehs, jhedstrom, marvil07, mikeryan, pcambra, Xano, YesCT, axoplasm, kgoel, dclavain, jeckman, alvar0hurtad0, Drupali, fastangel, gloob, jhedstrom, joshtaylor, mpgeek, alexpott: Migrate Drupal 6 to Drupal 8