support: Introduce editorconfig

EditorConfig[0] specifies how an IDE configures generic styling for files
for a project.  This is done by introducing a top-level `.editorconfig`
file within the repository.  This commit sets the Unikraft standards using
EditorConfig:

 * indentation using tabs with spacing of 8 characters;
 * max line lenfth of 75 characters for git commit messages;
 * max line length of 80 characters for standard files;
 * adding a new line to the end of files; and,
 * trimming of whitespace.

[0]: https://editorconfig.org

Signed-off-by: Alexander Jung <[email protected]>

squash

Reviewed-by: Simon Kuenzer <[email protected]>
Tested-by: Unikraft CI <[email protected]>
GitHub-Pull-Request: unikraft#209

Author: nderjung

.editorconfig

@@ -0,0 +1,14 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 8
+indent_style = tab
+max_line_length = 80
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[.git/**]
+max_line_length = 75
+