Add support for MSNBot, BingPreview, and AdIdxBot crawlers

[Copilot]

Adds detection for three additional Bing/Microsoft crawlers per their official crawler list: MSNBot, BingPreview, and AdIdxBot.

Changes

• Browser detection (parser-browsers.js): Added patterns for MSNBot, BingPreview, and AdIdxBot. Placed before BingCrawler to ensure specific patterns match first.
• Platform detection (parser-platforms.js): Added bot type classification with appropriate vendors (Microsoft for MSNBot, Bing for BingPreview/AdIdxBot).
• Constants (constants.js): Added aliases and mappings for the three new bots.
• Test cases (useragentstrings.yml): Added real user agent strings covering both numeric versions and alpha/beta suffixes.

Version handling

Regex pattern /(\d+(\.\d+)*[a-z]*)/i supports versions like "2.0", "2.1", and "2.0b" (with alpha/beta suffixes).

const parser = Bowser.getParser('msnbot/2.0b (+http://search.msn.com/msnbot.htm)');
parser.getBrowserName();     // "MSNBot"
parser.getBrowserVersion();  // "2.0b"
parser.getPlatformType();    // "bot"

Note: Googlebot and BingCrawler were already supported.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Build in recognition of search bot user agents</issue_title>
<issue_description>Feature Suggestion:
It seems that it would be relatively common use case to desire to know if the agent is a search bot, so building in the user agents for common search bots seems like a reasonable feature.

Google: https://support.google.com/webmasters/answer/1061943?hl=en
Bing: https://www.bing.com/webmaster/help/which-crawlers-does-bing-use-8c184ec0
</issue_description>

Comments on the Issue (you are @copilot in this section)

@lancedikson It's ok. Could you prepare a PR?

• Fixes Build in recognition of search bot user agents #116

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