Auto-create quotes after inserting the `=` sign after an attribute

[fbricon]

Same as the HTML language support:

Should honor the xml.preferences.quoteStyle setting.

[angelozerr]

I think the HTML ls manages this usecase with the closeTag custom request (they does some refactoring to manag eclose tag and quotes). We must allogn our closeTag request with the HTML LS.

[angelozerr]

We must replace closingTag request with autoInsert like https://github.com/microsoft/vscode/blob/81fff43fd6f9f5dd9c01508da30b16f35ed61933/extensions/html-language-features/client/src/htmlClient.ts#L46 which support auto close and equals insert.

[angelozerr]

We must replace our lemminx closingtag support with autoInsert https://github.com/microsoft/vscode/blob/81fff43fd6f9f5dd9c01508da30b16f35ed61933/extensions/html-language-features/server/src/modes/htmlMode.ts#L62

at https://github.com/eclipse/lemminx/blob/bcad686338416f7c6afd687006650c0a56b09e5a/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/XMLLanguageServer.java#L290