fix: SSO button link target [DET-10171]

[julian-determined-ai]

Description

See: https://hpe-aiatscale.slack.com/archives/CLCE8D998/p1709221849482189

The link for SSO did not wrap entirely around the button element. This fixes the issue.

Test Plan

1. Ensure that your UI is pointing to an SSO enabled cluster. For example our gcloud cluster.
2. On the sign in page ensure that clicking anywhere on the SSO sign in button sends you to the appropriate login page.

Commentary (optional)

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

Ticket

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[ashtonG]

lgtm -- looking forward, we really should have link buttons as part of the ui kit.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 42.45%. Comparing base (5367f4f) to head (5a0de8d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8925      +/-   ##
==========================================
- Coverage   47.17%   42.45%   -4.72%     
==========================================
  Files        1154      840     -314     
  Lines      175088   136240   -38848     
  Branches     2237     2235       -2     
==========================================
- Hits        82596    57845   -24751     
+ Misses      92334    78237   -14097     
  Partials      158      158              

Flag	Coverage Δ
harness	?
web	42.53% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
webui/react/src/pages/SignIn.tsx	0.00% <0.00%> (ø)

... and 314 files with indirect coverage changes