Feature/UI update

[Garywoo]

The UI for the import and export features were lacking the Salesforce Lightning Design System love 💔

I've updated both of these features to use this modern and standardised styling system, updating the look and feel of both of these areas, along with making some other minor usability tweaks.

Screenshots

Change Log

• Updated the UI of the Import & Export features to use the Salesforce Lightning Design System
  • Unified the Header.
  • Updated the loading spinner.
  • Relocated the help button to the header, in a familiar place for Salesforce users.

Export Feature

• Added icons to the autocomplete suggestions to visually denote data type, and to reveal relationships which can be expanded.
• Added confirmation dialogs when clearing the Query History or Saved Queries. No more accidentally losing your history.
• Bumped the number of recent queries in the Query History list from 20 to 100.
• Made autocomplete work after an uppercase FROM keyword - Fixes Keywords should be case insensitive on auto-complete sorenkrabbe/Chrome-Salesforce-inspector#189
• Hitting the F5 key now also runs the export. Frequent users of SSMS and other database tools rejoice!
• Tweaked some of the UI text to clarify the functionality of some features.
• Moved the lesser-used saved query clearing buttons into an expandable menu.

Import Feature

• Added original source column names to the field mapping section to help you understand what data is going where.
• Updated the execute button to dynamically change its text depending on the action being executed. No more clicking Import to update some records.
• Updated the field types in the Configure Import and Field Mapping sections to use relevant types. Quickly clearing the field value is now possible, and useful when mapping fields or selecting an object.