Hamburger menu js-free graceful degradation

[ivan-kocienski-gfsc]

Fixes #325

Description

When a user who has no js enabled, the hamburger menu becomes a link to a static navigation page.

Looks like

Tasks pending

• the hamburger menu link out-by-one pixel alignment
• some polish on the nav page
• content for the summaries

@geeksforsocialchange/developers

[aaaaargZombies]

nice solution, a bit of polish

• we're inheriting link styles on the button
• once JS kicks in switch the element to a button for better HTML semantics

[ivan-kocienski-gfsc]

Will get back to this on a later cycle. Have left comment on issue #325