widgets(table): implemented header and column borders

- Added the `header_border` and `col_border` to `TableContext`. Note, row borders don't work as well due to borders taking up an entire cell.
- Updated the `table.zig` example.

examples/table.zig

@@ -79,12 +79,15 @@ pub fn main() !void {
     var demo_tbl: vaxis.widgets.Table.TableContext = .{
         .active_bg = active_bg,
         .active_fg = .{ .rgb = .{ 0, 0, 0 } },
+        .row_bg_1 = .{ .rgb = .{ 8, 8, 8 } },
         .selected_bg = selected_bg,
         .header_names = .{ .custom = &.{ "First", "Last", "Username", "Phone#", "Email" } },
         //.header_align = .left,
         .col_indexes = .{ .by_idx = &.{ 0, 1, 2, 4, 3 } },
         //.col_align = .{ .by_idx = &.{ .left, .left, .center, .center, .left } },
-        .col_align = .{ .all = .center },
+        //.col_align = .{ .all = .center },
+        //.header_borders = true,
+        //.col_borders = true,
         //.col_width = .{ .static_all = 15 },
         //.col_width = .{ .dynamic_header_len = 3 },
         //.col_width = .{ .static_individual = &.{ 10, 20, 15, 25, 15 } },

src/widgets/Table.zig

@@ -64,6 +64,13 @@ pub const TableContext = struct {
     header_align: HorizontalAlignment = .center,
     // Column Alignment
     col_align: ColumnAlignment = .{ .all = .left },
+
+    // Header Borders
+    header_borders: bool = false,
+    // Row Borders
+    //row_borders: bool = false,
+    // Col Borders
+    col_borders: bool = false,
 };
 
 /// Width Styles for `col_width`.
@@ -233,6 +240,7 @@ pub fn drawTable(
             .y_off = 0,
             .width = .{ .limit = col_width },
             .height = .{ .limit = 1 },
+            .border = .{ .where = if (table_ctx.header_borders and idx > 0) .left else .none }
         });
         var hdr = switch (table_ctx.header_align) {
             .left => hdr_win,
@@ -292,6 +300,7 @@ pub fn drawTable(
             .y_off = 1 + row + table_ctx.active_y_off,
             .width = .{ .limit = table_win.width },
             .height = .{ .limit = 1 },
+            //.border = .{ .where = if (table_ctx.row_borders) .top else .none },
         });
         if (table_ctx.start + row == table_ctx.row) {
             table_ctx.active_y_off = if (table_ctx.active_content_fn) |content| try content(&row_win, table_ctx.active_ctx) else 0;
@@ -322,6 +331,7 @@ pub fn drawTable(
                     .y_off = 0,
                     .width = .{ .limit = col_width },
                     .height = .{ .limit = 1 },
+                    .border = .{ .where = if (table_ctx.col_borders and col_idx > 0) .left else .none },
                 });
                 const item_txt = switch (ItemT) {
                     []const u8 => item,