Improvement: Precalculate the cell content

[edisonhello]

• Fix a bug that the cell's height is miscalculated when there's a left-right-padding setting and the word is getting separated.

Cause: In print_row_in_cell, the text is wrapped (by word_wrap) and split (by split_lines) too early before checking the padding settings.

• Precalculate and cache the result of word_wrap and split_lines before calling print_row_in_cell to improve the printing complixity

Detail: In print_row_in_cell, word_wrap and split_lines will be called once for each cell each line they have. When the content of the cell and the number of lines are both large, the computation time will grow massively.

In this PR, the computation is moved before the actual printing procedure, so those functions won't get called multiple times for each cell, and also avoid the bug mentioned by using the correct line height in print_row_in_cell.

Further todo: the code in Row::get_cell_height is also similar to these, maybe we should reuse the code.

The example of the bug (the upper one is before, and the lower one is after):

Reproduce code:

Table table;

table.add_row({"abcde"});

table.format().width(10);
table.format().padding_left(4);
table.format().padding_right(4);

cout << table << endl;

Additional check for not breaking another sample:

I did a manual check for all the samples and hope there's no accident.

• Apply clang-format for all the files changed in this PR.