[Hristo313]

Closes #723

Update the Combo Template xplat topics

Also updated the samples:
Angular -> IgniteUI/igniteui-angular-samples#4077
React -> IgniteUI/igniteui-react-examples#1141
WC -> IgniteUI/igniteui-wc-examples#1312
Blazor -> IgniteUI/igniteui-blazor-examples#1360

Checklist:

• check topic's TOC/menu and paragraph headings
• Include TOC topic labels in the topic content when it has a valuable update, is new, or is considered preview / beta
• link to other topics using ./page.mdx or ../relative/path.mdx (.mdx extension required)
• at the References section at the end of the topic add links to topics, samples, etc
• reference API documentation instead of adding a section with API

• use valid component names - [Data] Grid, IgxSelectComponent, <igx-combo>
• use spell checker tool (VS Code, Grammarly, Microsoft Editor)
• add inline code blocks for the names of classes / tags / properties
• add language descriptor for the code blocks
• check if links function by running the check-api/mdx npm commands
• check if sample is working and fully visible in the topic
• check if sample is working and fully visible in the StackBlitz
• check if code blocks match the code in StackBlitz demo
• add or update meaningful llms.description metadata and run npm run check:llms-metadata

• follow SEO guidelines to fill topic's metadata (SEO guidelines)

• do not resolve requested changes (leave that to the reviewer)

[DiLazarova]

Review for Combo Templates - React/ Chrome

1. Live Demo: first when loading the page there should be no selection and the dropdown should be open:

2. The Dropdown should be open so that the user going through all the templates, can see how they are displayed:

3. The Combo component should be in the center of the Sample Viewer Frame

4. Please double check for hardcoded colors and text styles!

• There are hardcoded text in the Header template - "Destinations by region" and "Select all" should be as follows: Destinations by region - subtitle 2 - 14/24 (relevant for each theme), Select all - other/button 14/16
• In Footer template - "2 selected" and "Clear" - should be Body2- 14/20 and other/button 14/16
• "Selection" panel, title and list - should be subtitle 2 and body 2 for Material - Titilium font and the relevant fonts for other themes