Refs #10260 Remove usage of LoadParameterFile::execManually

Replace all external calls to this static method with use of a child
algorithm instead.
Refs #10260 Remove LoadParameterFile::execManually
Refs #10260 Improve LoadParameterFile progress reporting
Refs #10260 Optimise setComponentLinks

Internally Poco::XML::NodeList::item performs an O(n) linked-list
traversal to look up an item by index. We were calling item within an
O(n) loop, pushing our performance up to O(n^2). Let's not do that.
Let's traverse the DOM ourselves at O(n).

On my machine this brought the execution time of LoadParameterFile down
from ~1,400 seconds to ~9 seconds. That's about 140x faster.
Refs #10260 Fix doxygen warning
Merge remote-tracking branch 'origin/feature/10260_loadparamfile_report_progress'