[Emotion] EuiModal

[daveyholler]

Acceptance criteria

• All SCSS files have been removed from the component(s) directory
• All SCSS overrides have been removed from the Amsterdam theme
• Any dependent components are identified in a new issue
• Changelog is updated
• Breaking changes are identified and broadcast to consumers

Checklists

Kibana usage

• Search Kibana's codebase for {euiComponent}- (case sensitive) to check for usage of modifier classes
  • If usage exists, consider converting to a data attribute so that consumers still have something to hook into

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General

• Output CSS matches the previous CSS (works as expected in all browsers)
• Rendered className(s) read as expected in snapshots and browsers
• Checked component playground

  NOTE: Class components wrapped in withEuiTheme need to pass true as the second argument to its propUtilityForPlayground in src-docs/src/views/{component}/playground.js

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Unit tests

• shouldRenderCustomStyles() test was added and passes with parent component and any nested childProps (e.g. tooltipProps)
• Removed any mount()ed snapshots in favor of render() or a more specific assertion

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Sass/Emotion conversion process

• Converted all global Sass vars/mixins to JS (e.g. $euiSize to euiTheme.size.base)
• Removed or converted component-specific Sass vars/mixins to exported JS versions
• Listed var/mixin removals in changelog
• Ran yarn compile-scss to update var/mixin JSON files
• Simplified calc() to mathWithUnits if possible (if mixing different unit types, this may not be possible)
• Added an @warn deprecation message within the global_styling/mixins/{component}.scss file
• Removed component from src/components/index.scss
• Deleted any src/amsterdam/overrides/{component}.scss files (styles within should have been converted to the baseline Emotion styles)

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CSS tech debt

• Wrapped all animations or transitions in euiCanAnimate
• Used gap property to add margin between items if using flex
• Converted side specific padding, margin, and position to -inline and -block logical properties (check inline styles as well as CSS)

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DOM Cleanup

• Did NOT remove any block/element classNames (e.g. euiComponent, euiComponent__child)
• SEARCH KIBANA FIRST: Deleted any modifier classNames or maps if not being used in Kibana.

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Kibana due diligence

• Pre-emptively check how your conversion will impact the next Kibana upgrade. This entails searching/grepping through Kibana (excluding **/target, **/*.snap, **/*.storyshot for less noise) for eui{Component} (case sensitive) to find:
• Any test/query selectors that will need to be updated
• Any Sass or CSS that will need to be updated, particularly if a component Sass var was deleted
• Any direct className usages that will need to be refactored (e.g. someone calling the euiBadge class on a div instead of simply using the EuiBadge component)

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Extras/nice-to-have

• Documentation pass:
  • Converted any remaining .js docs files to TS
  • Misc cleanup of docs code (e.g. combine imports to single from '../src', replace <React.Fragment> with <>)
• Reduced specificity where possible (usually by reducing nesting and class name chaining)
• Check for issues in the backlog that could be a quick fix for that component
• Optional component/code cleanup: consider splitting up the component into multiple children if it's overly verbose or difficult to reason about

[daveyholler]

#6321