Fix ssr error by only importing altcha on the client side

[artlowel]

References

• Fixes SSR for Item pages is currently broken (9.0 only) #4145

Description

The issue was caused by the fact that altcha was loaded server side, and that's not supported. When it tries to define the altcha-widget the server-side throws an exception.

I fixed it by removing the import everywhere, and putting it in browser-app.config.ts

I also removed an unnecessary ngVar, as they can be bad for performance.

Instructions for Reviewers

Ensure that the ssr error is gone, and that the altcha captchas still work.

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[kshepherd]

+1 thanks @artlowel and sorry for my oversight on the ssr compatibility.
The changes look good, including the tidyup of challegeHref usage, and I've confirmed ALTCHA is still working on the request-a-copy form.