Split colors into separate files

[hbons]

This pull request splits the colors into separate files for better organization and maintainability. It also splits the excessively long lines over multiple lines for better readability,

Created a new folder colors in vs/platform/theme/common with the following files:

baseColors.ts
chartsColors.ts
editorColors.ts
inputColors.ts # buttons, fields, checkboxes
listColors.ts # lists, tables, trees
menuColors.ts
minimapColors.ts
miscColors.ts # everything else
quickpickColors.ts
searchColors.ts