Add Multi-Language Descriptions for 'Switch' Component and Update Message Assistant Placeholder (#2450)

### What problem does this PR solve?

_This PR addresses the need to describe the "Switch" component across
different languages and corrects a misleading description for a
placeholder message not exclusively tied to a specific assistant type.
By providing clearer and more accurate descriptions, this PR aims to
improve user understanding and usability of the Switch component and the
"Message Resume Assistant..." placeholder in a multilingual context._

### Explanation of Changes

1. **Added Descriptions for "Switch" Component**: 
- Descriptions were added for the "Switch" component in three different
locales:
- **English (EN)**: Provides a concise description of what the "Switch"
component does, focusing on its ability to evaluate conditions and
direct the flow of execution.
- **Simplified Chinese (ZH)**: Translated the English description into
Simplified Chinese to cater to users who prefer this locale.
- **Traditional Chinese (ZH-Traditional)**: Added a Traditional Chinese
version of the description to support users in regions that use
Traditional Chinese.
   
2. **Corrected "Message Resume Assistant..." to "Message the
Assistant..."**:
- Updated the description from "Message Resume Assistant..." to "Message
the Assistant..." in the English locale. This correction makes the
description more generic and accurate, reflecting the placeholder's
broader functionality, which is not limited to Resume Assistants. It now
clearly communicates that the placeholder can be used with various types
of assistants, not just those related to resumes.

### Type of change

- [ ] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)
- [x] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

web/src/locales/en.ts

@@ -329,7 +329,7 @@ The above is the content you need to summarize.`,
       chat: 'Chat',
       newChat: 'New chat',
       send: 'Send',
-      sendPlaceholder: 'Message Resume Assistant...',
+      sendPlaceholder: 'Message the Assistant...',
       chatConfiguration: 'Chat Configuration',
       chatConfigurationDescription:
         ' Here, dress up a dedicated assistant for your special knowledge bases! 💕',
@@ -659,6 +659,7 @@ The above is the content you need to summarize.`,
       messageDescription:
         "A component that sends out a static message. If multiple messages are supplied, it randomly selects one to send. Ensure its downstream is 'Answer', the interface component.",
       keywordDescription: `A component that retrieves top N search results from user's input. Ensure the TopN value is set properly before use.`,
+      switchDescription: `A component that evaluates conditions based on the output of previous components and directs the flow of execution accordingly. It allows for complex branching logic by defining cases and specifying actions for each case or default action if no conditions are met.`,
       wikipediaDescription: `This component is used to get search result from wikipedia.org. Typically, it performs as a supplement to knowledgebases. Top N specifies the number of search results you need to adapt.`,
       promptText: `Please summarize the following paragraphs. Be careful with the numbers, do not make things up. Paragraphs as following:
         {input}