util: add custom collector for ImmutableList.
util: Table: use Collectors#toImmutableList().
util: Table: compute column widths only once.
util: Table: encapsulate stuff in FormattingInfo.
util/table: move Table into its own subpackage.
util/table: Table nested classes -> top level.
util/table: move col width computers to util class
util/table: promote RowBuilder to top level.
util/table: rename ColumnWidthComputer

...to FormattingInfoComputer.
util/table: make FormattingInfoComputer inner.
util/table: hide col widths in ColumnWidthInfo.
util/table: add a FormattingInfo Builder class.
util/table: no more need for ColumnWidthInfo.
util/table: hide Row.columns behind getter.
util/table: simplify a loop.