Upload Directories via Web

This implements the option to choose directories when uploading files via the Web UI (The most important part of #52).

When you choose a directory, its file and sub-directory structure will be maintained.

Tested with the latest Safari, Firefox, and Chrome.

Additionally, the Deno version was updated, which required some accessibility improvements as well.

components/expenses/MainExpenses.tsx

@@ -729,12 +729,14 @@ export default function MainExpenses({ initialBudgets, initialExpenses, initialM
                 <button
                   class={`text-white block px-4 py-2 text-sm w-full text-left hover:bg-slate-600`}
                   onClick={() => onClickCreateExpense()}
+                  type='button'
                 >
                   New Expense
                 </button>
                 <button
                   class={`text-white block px-4 py-2 text-sm w-full text-left hover:bg-slate-600`}
                   onClick={() => onClickCreateBudget()}
+                  type='button'
                 >
                   New Budget
                 </button>
@@ -746,12 +748,14 @@ export default function MainExpenses({ initialBudgets, initialExpenses, initialM
                 <button
                   class={`text-white block px-4 py-2 text-sm w-full text-left hover:bg-slate-600`}
                   onClick={() => onClickImportFile()}
+                  type='button'
                 >
                   Import
                 </button>
                 <button
                   class={`text-white block px-4 py-2 text-sm w-full text-left hover:bg-slate-600`}
                   onClick={() => onClickExportFile()}
+                  type='button'
                 >
                   Export
                 </button>