Update gradle documentation, split it into two pages.

[HerbertsVaadin]

Solves #4222

Changes:

• Removed the "Developing in Eclipse IDE" section - unnecessary, not Vaadin specific information, if you use Gradle, and have chosen to use Gradle, and use Eclipse, you probably know how to import and run gradle application in Eclipse IDE.
• Reduced requirements section to a note - unecessary to have so much detail.
• Reduced starter project contents to only gradle-related files
• Reduced section "The most important files and folders are as follows" to only reference gradle related files, since the rest is the same between other build tools.
• Simplified compile section, referenced configuration page
• Removed warning about Gretty + jcenter, as it is no longer relevant.
• Created new page under flow/configuration specific to Gradle configuration properties.
• Refactored Configuring repositories section, removed focus from pre-releases.
• Removed the build file "Other Configuration" section, as its no longer valid.

[github-actions]

AI Language Review

The key differences and issues in the updated documentation involve a few adjustments:

1. Additional Information on Gradle Configuration: There is a new reference to the "Gradle Configuration Properties" page. Ensure that this page is available and accurately linked in the text.

2. Requirements Section: The updated version includes a note on installing Node.js and npm automatically. It's advisable to verify this behavior with the actual plugin functionality. Also, ensure consistency in mentioning minimum versions of Gradle across the document.

3. Version Update for Plugins: Plugin versions have been updated (e.g., from Gretty version 3.0.3 to 4.1.1). Ensure these reflect the correct versioning needed for compatibility with other components (such as Vaadin).

4. "Gradle Files in Starter Projects" Section Created: A new section outlining Gradle-related files in starter projects has been added. Ensure it aligns with other sections that reference or elaborate on build scripts, especially if referencing specific files or functionality.

5. Consistency in Terminal Commands: In various sections, both ./gradlew and gradlew are specified for Unix/Mac and Windows bash environments. Maintain uniformity in explaining this to avoid any confusion.

Check the integration within the documentation for all new references and sections created, ensuring they provide value and correctness in guidance.

[HerbertsVaadin]

I think the remaining AI Language Review suggestions can be ignored, I think it's unaware that the original document has been split into two, and more focused / less-verbose approach of the document is desired.

[mcollovati]

It could be worth it adding that install happens only if Node is not already installed or if it does not match the minimum version required by Vaadin.

[mcollovati]

I'm not so skilled in Gradle, but at least our starter seems to provide a different plugin configuration.

It has the version pinned in settings file (https://github.com/vaadin/base-starter-gradle/blob/9a8284e07d02e0f6f346b49accbebd902e50865a/settings.gradle#L7) and only definition in the build script (https://github.com/vaadin/base-starter-gradle/blob/9a8284e07d02e0f6f346b49accbebd902e50865a/build.gradle#L15), no apply at all.

So the question is if it would be enough to set the snapshot version in settings in combination with the configuration of the pre-release repository.

I'm not sure what we should suggest in the docs. Maybe @mvysny can provide some insight

[HerbertsVaadin]

I've updated to a modernized version, seems like the "apply" approach is historic. Please check.