fix(ui): update default avatar and change scrollbar width

src/app/header/header.component.html

src/app/header/header.component.scss

src/app/profile/profile.component.html

src/app/profile/profile.component.scss

src/app/shared/components/svg-icon/svg-icon.component.scss

src/assets/avatar/defaultAvatar.svg

src/assets/avatar/sprite.svg

src/styles.scss