This PR fixes l10n issue when months names are being used in incorrect form in CupertinoDatePicker in CupertinoDatePickerMode.yearMonth (#130930).

The idea of this proposal is to add an optional parameter `standalone` for `CupertinoLocalizations.datePickerMonth` to be able to choose when to use months names in base form (intl DateSymbols.STANDALONEMONTHS) and when in day-dependent form (intl DateSymbols.MONTHS)

<details>
<summary>Before</summary>

<img width="366" alt="image" src="https://github.com/flutter/flutter/assets/32621121/1dd54fa7-6dd9-4053-889b-57134c145432">

<img width="387" alt="image" src="https://github.com/flutter/flutter/assets/32621121/c176070e-73e4-49d3-883b-ba31eca6d1d7">

</details>

<details>
<summary>After</summary>

<img width="369" alt="image" src="https://github.com/flutter/flutter/assets/32621121/255594f1-219d-4bd4-9b75-1012912f8ab0">

<img width="378" alt="image" src="https://github.com/flutter/flutter/assets/32621121/16bbb41f-3f62-4446-bf41-e27140b649a9">

</details>

In native iOS, users are able to select text and initiate a share menu, which provides several standard services, such as copy, sharing to social media, direct ability to send to various contacts through messaging apps, etc. 

https://github.com/flutter/engine/assets/36148254/d0af7034-31fd-412e-8636-a06bbff54765

This PR is the framework portion of the changes that will allow Share to be implemented.
The corresponding merged engine PR is [here](https://github.com/flutter/engine/pull/44554)
This PR addresses https://github.com/flutter/flutter/issues/107578
More details are available in this [design doc](https://github.com/flutter/engine/pull/flutter.dev/go/add-missing-features-to-selection-controls)

This PR adds framework support for the Search Web feature in iOS. 

https://github.com/flutter/flutter/assets/36148254/c159f0d9-8f14-45e7-b295-e065b0826fab

The corresponding merged engine PR can be found [here](https://github.com/flutter/engine/pull/43324).
This PR addresses https://github.com/flutter/flutter/issues/82907 
More details are available in this [design doc](https://docs.google.com/document/d/1QizXwBiO-2REIcEovl5pK06BaLPOWYmNwOE5jactJZA/edit?resourcekey=0-1pb9mJiAq29Gesmt25GAug)

This PR adds framework support for the Look Up feature in iOS. 

https://github.com/flutter/flutter/assets/36148254/d301df79-4e23-454f-8742-2f8e39c2960c

The corresponding merged engine PR can be found [here](https://github.com/flutter/engine/pull/43308).
This PR addresses https://github.com/flutter/flutter/issues/82907 
More details are available in this [design doc.](flutter.dev/go/add-missing-features-to-selection-controls)

This is the same PR as https://github.com/flutter/flutter/pull/130532, this is an attempt to fix the Google Testing issue

## Description

Modifies the semantic label for popup and context menus to be "Dismiss menu" instead of just "Dismiss".

## Related Issues
 - Fixes https://github.com/flutter/flutter/issues/118994

## Tests
 - Updated tests

Localize the 'No Replacements Found' spell check string

fixes Show Week Day in CupertinoDatePicker with CupertinoDatePickerMo…

* Use `curly_braces_in_flow_control_structures` for `animation`

* Use `curly_braces_in_flow_control_structures` for `cupertino`

* fix comments

Migrate flutter_localizations to null safety.

* migrate some cupertino files to nullsafety

* address review comments

* Add punctuation for unterminated sentences in doc comments

* Addressing review nit

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

* fix some bad indentations

* remove suspicious line

* Fix internationalization issues with cupertinoTextSelectionControls

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

Fixes #21250

add cupertino localizations abstract class and the default cupertino localizations in US English.