Adds i18n config test to be used in widget PDV

[vijetmahabaleshwar-okta]

• We use oidc-middleware custom sign-in page test as PDV for widget global CDN
• This PR extends the test to include i18n options to catch issues like this
• Since we already run this test on bacon as PDV, adding i18n test to this repo will get us more coverage without any setup effort (as opposed to adding it in widget repo, in which case we have to setup new tests in bacon)

PR Checklist

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• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Adding Tests
• Build related changes
• CI related changes
• Documentation changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

Reviewers

[haishengwu-okta]

Thanks! a couple of nits.

Question:
what's usage of harness/start-custom-login-server.js?
I assume specs/custom-login-page.js is for running test.
(The initial code looks identical and wonder if could be consolidated.)

[haishengwu-okta]

nit: looks like options can be const

[haishengwu-okta]

nit: would be simplified a little bit as

let widgetVersion = '4.4.1';

if (env.NPM_TARBAR_URL) {
   widgetVersion = version;
}

const cdnUrl = `https://global.oktacdn.com/okta-signin-widget/${widgetVersion}`;

[vijetmahabaleshwar-okta]

Thanks! a couple of nits.

Question:
what's usage of harness/start-custom-login-server.js?
I assume specs/custom-login-page.js is for running test.
(The initial code looks identical and wonder if could be consolidated.)

This is if a user wants to start a custom login server without running tests.
I will check if we can consolidate this code, or if we even need this NPM_TARBALL_URL logic here at all.