V6 ESM, Types, Skip tags

[not-matt]

I wanted to get this library working in ESM for V6. Apologies for large PR - I needed to get the v6 library working for me asap.

• Added new subpath exports in package.json for fast-xml-parser/v6, enabling direct ESM and type-safe imports for v6 classes and types.
• Updated documentation (docs/v6/1.GettingStarted.md, docs/v6/3.Options.md, docs/v6/4.OutputBuilders.md) to provide usage examples for new types and ESM imports
• Added and improved TypeScript typings for v6, including V6ParserOptions and V6BuilderOptions
• Use ESM import/export style across v6 source files
• Bumped strnum version

Bug Fixes:

• Fixed a bug in Xml2JsParser where trailing whitespace could cause a false positive for unexpected data at the end of the document. (Related issue but this fix is only in v6 #704 )
• Resolves #763

New Features:

• Implemented skip tags functionality. Tags in the options.skip list will be completely ignored, which speeds up parsing in some situations.

Type

• [x] Bug Fix
• [x] Refactoring / Technology upgrade
• [x] New Feature

Note : Please ensure that you've read contribution guidelines before raising this PR. If your PR is in progress, please prepend [WIP] in PR title. Your PR will be reviewed when [WIP] will be removed from the PR title.

[guardrails[bot]]

:warning: We detected 2 security issues in this pull request:

Vulnerable Libraries (2)

Severity	Details
High	[email protected] upgrade to: >=2.4.1
Low	pkg:npm/[email protected] (t) upgrade to: > 8.57.0

More info on how to fix Vulnerable Libraries in JavaScript.

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[amitguptagwl]

I really appreciate your effort. But since it is a big change, I can create a separate branch to merge the changes to so I can test them locally first. Can you please remove change to yarn.lock, any generated bundle file, or package file. If you really need them, you can mention the changes to PR and I'll do that. Thanks

[amitguptagwl]

I've created a new branch 'v6' for this change