Add IContextSource as parameter to ChangeTags::formatSummaryRow

Using IContextSource avoids the use of $wgLang and wfMessage which make
use of global $wgTtle.

Add IContextSource as parameter to ChangeTags::formatSummaryRow to avoid
globals. Define an IContextSource instance in all functions which
reference ChangeTags::formatSummaryRow and pass it in ChangeTags::formatSummaryRow
function call.

Also make the default value of IContextSource $context as null in
parameter, to avoid breaking changes for old callers in extensions.

Document default null value of IContextSource and add a @note to prefer
IContextSource over null value.

Remove trailing whitespace, and make code order according to parameter
order.

Bug: T105648
Change-Id: Ib54a6a96b73f6cd8fcdf8e520db2448a1e811cfa