feat(core): allow soft wraps between CJK characters

[imnotlxy]

Line wraps are allowed between any CJK characters. Take this new test case as an example:

test "TextBufferView word wrapping - CJK graphemes fill line after punctuation" {
    const pool = gp.initGlobalPool(std.testing.allocator);
    defer gp.deinitGlobalPool();
    const link_pool = link.initGlobalLinkPool(std.testing.allocator);
    defer link.deinitGlobalLinkPool();

    var tb = try TextBuffer.init(std.testing.allocator, pool, link_pool, .wcwidth);
    defer tb.deinit();

    var view = try TextBufferView.init(std.testing.allocator, tb);
    defer view.deinit();

    try tb.setText("一二，三四五六七");

    view.setWrapMode(.word);
    view.setWrapWidth(10);

    const lines = view.getVirtualLines();
    try std.testing.expectEqual(@as(usize, 2), lines.len);
    try std.testing.expectEqual(@as(u32, 10), lines[0].width_cols);
    try std.testing.expectEqual(@as(u32, 6), lines[1].width_cols);
}

Before:

一二， <- line wrapped here
三四五六七

After:

一二，三四 <- line wrapped here
五六七