C: Use Arena Allocator

[marcoroth]

We have a decent and working Arena Allocator Implementation in hb_arena.c that we are not using yet in the lexer, parser, and other parts of the C codebase in src/ yet.

• C: Switch to arena allocator #583
• C: Remove memory.c implementation in preparation for arena allocator #611
• C: Implement rudimentary arena allocator hb_arena.c #623
• C: Use arena allocator in lexer #658
• C: Use Arena Allocator in hb_string_to_c_string function #674
• C: Inline size_t_to_string function #676
• C: Move hb_arena.c to src/util/ #707
• C: Implement page-based architecture for Arena Allocator #708
• C: Implement merging arena pages #719
• C: Add Visual Arena Debug Helpers #725
• C: Use Arena Allocator for Lexing and Parsing #726
• C: Allow to control memory allocation strategy #729
• C: Use hb_string_T when initializing new tokens #798
• C: Add hb_buffer_init_arena for allocating a buffer using the arena allocator #862

Let's adopt the Arena Allocator in favor of manually allocating memory in all places where it makes sense.

[marcoroth]

Resolved via #726