(#530) Add test cases to exercise print methods for mini-allocator metadata pages and for trunk verbose logging.

[gapisback]

This commit adds new print function to drive the functions for printing keyed / unkeyed metadata pages of the mini-allocator. Existing test cases are enhanced as follows to eventually exercise these print methods.

• Extend splinter_test:test_splinter_print_diags() to print just one routing-filter page hanging off trunk's root node. New function trunk_print_root_nodes_filter_metapages() will exercise the print function that will walk through routing filter metadata pages for one pivot key and eventually calls mini_unkeyed_print().

• Modularize code in btree_stress_test.c to carve out code that is used to build new unit-test case, test_btree_print_diags(). First, this invokes btree_print_tree(), to see outputs of packed BTree node. Then, invokes mini_keyed_print(), to print keyed mini-allocator's metadata pages.

• Add bunch of print functions in trunk.c to find out routing filter metadata pages and to invoke underlying print methods on such pages.

NOTE: This is a draft PR to discuss the changes with Alex & Rob.

[Updated 2.1.2023]: Fixed a bug. Much of the driving functions seem to work ok. The print outputs from updated test cases for keyed and unkeyed mini-allocator's metadata pages for "real-data" (generated by inserting lots of rows into trunk or BTree) seem to work fine.

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[gapisback]

Draft PR. This dev work was surfaced as 2-part PRs which were internally discussed. There was no interest in absorbing this work to /main.

Abandoned.