feat: add file name change functionality

1. Added file name input text box to change the file name before downloading. 2. Added reset button to reset file name to original value. 3. Added error text to display errors dynamically when the file name is invalid. File name is invalid for following cases. - File name shouldn't contain invalid characters ("/", "\\", ":", "*", "?", """, "<" and ">"). - File name shouldn't be any of the reserved names. - File name shouldn't be empty. 4. Placeholders in the file name input will be replaced by their respective timestamp values. Placeholders and their values are given below. - {YYYY} - current year - {MM} - current month - {DD} - current date - {hh} - current hour - {mm} - current minute