Use stack frame tracking for non-recursive DFS algorithms

[SpectraL519]

In both GL and HGL modules:

• Added an Extension template parameter and an ext member to the search_node types
• Aligned the dfs templates to properly utilize an extended search_node type to perform a true post-order execution of the post_visit callback
• Replaced the use of std::vector for single-root ranges in concrete algorithms with std::array

In the GL module:

• Replaced the dedicated dijkstra_search_node type with a simple extension of the generic search_node type

In the HGL module:

• Replaced the old search_tree alias for a vector of search nodes with a dedicated search_tree type with its dedicated, smaller nodes

[SpectraL519]

ok