seperate hashing with no concat and fix "hash" option

[theo-barfoot]

Summary of Changes:

Previous State:

The previous HTML file had the following behaviour:

• The "hash and exclude" option concatenated all selected columns and hashed them together.
• The "hash" option did not hash the contents of the column, but just an empty string

Changes Made:

Separate Hashing for Each Column:

• Modified the code to hash each selected column separately instead of concatenating them.
• Added a new column with the original column name suffixed by "_hash" for each hashed column.

Handling Options Correctly:

• Hash: Added a new column with the hashed value (column name suffixed with "_hash") and retained the original column, fixing "Hash" only option doesn't seem to work as expected. #10
• Hash and Exclude: Added a new column with the hashed value (column name suffixed with "_hash") and removed the original column from the unidentifiable spreadsheet.

Added Hash Input Box:

NOTE: This feature was already added to the main branch as it was a solution required in real time

• Added a new section with a text input box and a button to hash the input using SHA-1.
• Displayed the first 10 characters of the hash below the input box when the button is clicked.