Add .gitattributes to "Content Types"

[bohni]

Description

As with .gitignore, the file .gitattibutes should be treated as text and opened with Eclipse Text editor.

see

egit/org.eclipse.egit.ui/plugin.xml

Lines 7991 to 7996 in 856a0dc

	<content-type
	id="org.eclipse.egit.contenttype.gitignore"
	base-type="org.eclipse.core.runtime.text"
	file-names=".gitignore"
	priority="normal"
	name="%GitIgnoreContentTypeName"/>

Motivation

Double click on the file in "Project Explorer" file tree will open the OS' "select application to open" dialog or the associated system editor instead of Eclipse Text Editor

Alternatives considered

No response

Additional context

No response