feat: add a dismissible conversion change warning

[IanKrieger]

Lets the end user know conversions have stricter enforcement:

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[lukaslevert]

Sharing my feedback from Slack, but it's not a blocker. I'd prefer to display the link more cleanly as one of these:

Ads Help Center
ads-help.brave.com

[github-actions]

[puLL-Merge] - brave/ads-ui@1249

Description

This PR makes significant changes to the conversion tracking functionality in the Brave Ads UI. It simplifies the conversion setup process, updates the user interface, and adds a new alert about changes to conversion reporting.

Changes

Changes

1. src/components/Conversion/ConversionDisplay.tsx:

   • Removed "Conversion Type" field
   • Reordered fields to show URL Pattern first
   • Changed "Observation Window" to "Conversion Observation Window"

2. src/components/Conversion/ConversionFields.tsx:

   • Removed radio control for conversion type
   • Updated helper text for observation window
   • Added LearnMoreButton to observation window field

3. src/locales/*.po:

   • Updated translations for various languages to reflect changes in the UI

4. src/user/views/adsManager/types/index.ts:

   • Updated initial conversion values: type is now "postclick" by default, observation window is 30 days

5. src/user/views/adsManager/views/advanced/components/adSet/fields/ConversionField.tsx:

   • Updated helper text for URL input
   • Changed UI for adding/removing conversion tracking
   • Replaced text link with a button for removing conversion tracking

6. src/user/views/user/CampaignView.tsx:

   • Added ConversionAlert component to the campaign view

7. src/user/views/user/ConversionAlert.tsx:

   • New file: Added a new alert component to inform users about changes in conversion reporting

Possible Issues

1. The removal of the conversion type selection (post-view vs post-click) might affect existing campaigns or reporting. It's unclear how this change will be handled for existing data.

2. The default 30-day observation window might not be suitable for all advertisers and could lead to confusion if not clearly communicated.

Security Hotspots

No significant security issues were identified in this change. However, ensure that the new ConversionAlert component doesn't expose any sensitive information and that the link to the help center is correctly implemented to prevent potential phishing attempts.