Add aria-label to aside landmarks on home page (Fixes #15000)

[alexgibson]

One-line summary

Gives each <aside> landmark on the home page a unique label for screen readers.

Issue / Bugzilla link

#15000

Testing

http://localhost:8000/en-US/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.64%. Comparing base (d32bb17) to head (56b939b).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #15016   +/-   ##
=======================================
  Coverage   77.64%   77.64%           
=======================================
  Files         162      162           
  Lines        8341     8341           
=======================================
  Hits         6476     6476           
  Misses       1865     1865           

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[janbrasna]

Can more banner instances appear on the same page? You may run into the same labelling ambiguity in such case.

[alexgibson]

Thanks for the suggestions, updated!

[stephaniehobson]

R+ 🏷️

[janbrasna]

Would it make sense to also use this newly added string as a legend for fieldset.mzp-c-newsletter-content there, that's missing one?

bedrock/bedrock/newsletter/templates/newsletter/includes/form.html

Lines 35 to 38 in 3e8f11b

	<fieldset class="mzp-c-newsletter-content">
	<div class="mzp-c-form-errors {% if not form.errors %}hidden{% endif %}" id="newsletter-errors" data-testid="newsletter-error-message">
	{{ form.non_field_errors()|safe }}
	<ul class="mzp-u-list-styled">