Improve search input on mobile

[valtlai]

This does two things to optimize the search input on mobile browsers:

• Disables the autocapitalization of the first letter as that does not make sense for search terms.
• Shows the Search icon/label on the mobile keyboard instead of the Go icon/label.

Before:

After:

[bglw]

Nice! Good calls. To keep this in one PR, would you be open to adding these attributes to the (upcoming) modular UI input as well?

Relevant input:

pagefind/pagefind_ui/modular/components/input.js

Line 90 in 281ffbb

this.inputEl = new El("input").id(`pfmod-input-${id}`).class("pagefind-modular-input").addTo(wrapper);

(All good if not! I can jump in tomorrow and add it to the branch before merging)

[valtlai]

To keep this in one PR, would you be open to adding these attributes to the (upcoming) modular UI input as well?

Done.