some more color changes, re #2739

public/assets/images/icons/blue/bullet-arrow.svg

public/assets/images/icons/blue/bullet-dot.svg

public/assets/images/icons/blue/bullet-double-arrow.svg

public/assets/images/icons/blue/bullet-line.svg

public/assets/images/icons/blue/category-draft.svg

public/assets/images/icons/blue/category-others.svg

public/assets/images/icons/blue/category-portfolio.svg

public/assets/images/icons/blue/category-task.svg

public/assets/images/icons/blue/category-template.svg

public/assets/images/icons/blue/content2.svg

public/assets/images/icons/blue/oer_elearning.svg