Spacing improvements in All content's <header> area

[fcoveram]

Problem

The "All content" results page has an unbalanced space in the result label area, between header and content links, that makes the layout look odd while resting space for more result items at the same time.

Here are two screenshots highlighting the area in blue.

And here screenshots for all breakpoints.

Description

The following spacing and text style changes can improve the layout:

• Reducing the line height of Heading 1 text style from 1.3 to 1. This library change will be updated in Figma's Design Library as well.
• Apply Heading 2 text style to <h1> on md breakpoint.
• Change the paddings of <header> element where h1 is placed to be 8px for top and 24px for bottom.
• Hide the <header> on xs and sm as the element adds unnecessary space. Here is a screenshot from Firefox's inspector.

I updated all layouts in Views page in the Design Library for reference.

Additional context

This request is in line with the improvements requested in #2078 that were identified during #1178