Fair amount of typos spotted and fixed. Some of them are in comments, some of them are in code and some of them are in nondart files.

There is no need for issues since it's a typo fix.

I have doubts about [packages/flutter_tools/lib/src/ios/core_devices.dart](https://github.com/flutter/flutter/compare/master...anisalibegic:flutter:master#diff-fdbc1496b4bbe7e2b445a567fd385677af861c0093774e3d8cc460fdd5b794fa), I have a feeling it might broke some things on the other end, even though it's a typo.

### Description

This PR intends to update `DraggableScrollableSheet` docs for Web and Desktop platforms. On these platforms, the vertical dragging gesture does not provide natural behavior similar to other desktop applications. 

By adding a note before the sample code so users are aware that the sample code will not work as expected on Desktop and Web. Also, refer to the instructions if they still want to implement it on these platforms.

### Related issue

Fixes https://github.com/flutter/flutter/issues/111372