Minor improvements in the new project creation window

Changes

• Added a warning about missing libraries in the target directory when attempting to create a new project;
• Added toggle functionality for the Create button's availability based on the emptiness of all TextBoxes. Previously, it was possible to click the Create button with empty values, which caused the application to crash;
• Added forced addition of the .opj extension when clicking the Create button. Previously, it was possible to create projects without an extension;
• Removed the check for nametextbox.TextLength == 0, as the Create button will not be enabled if the name is empty, making the length check unnecessary.