arena: add public allocation interface #311

Job	Run time
CentOS 7 build to confirm no issues once used downstream	41s
Debian Buster build to confirm no issues once used downstream	33s
Build sources on amd64 for windows-latest	16s
Build sources on MSYS2 for windows-2022	3m 19s
Build sources on MSYS2 for windows-latest	3m 26s
Build sources on amd64 for windows-2022	17s
Build sources with GNU 17	11s
Build sources with GNU 99	20s
Build sources on arm64 for ubuntu-latest - clang	7m 2s
Build sources on arm64 for ubuntu-latest - gcc	4m 41s
Build an installed CFL consumer	17s
Build downstream consumer cmetrics	33s
Build downstream consumer ctraces	24s
Build downstream consumer fluent-bit	3m 18s
Build downstream consumer cprofiles	45s
Build sources on amd64 for ubuntu-latest - clang	21s
Build sources on amd64 for macos-latest - clang	21s
Build sources on amd64 for ubuntu-latest - gcc	13s
Build sources on amd64 for macos-latest - gcc	21s
Build with various code analysis tools (clang-sanitize-safe-stack)	25s
Build with various code analysis tools (clang-sanitize-address)	36s
Build with various code analysis tools (clang-sanitize-dataflow)	26s
Build with various code analysis tools (clang-sanitize-memory)	38s
Build with various code analysis tools (valgrind)	24s
Build with various code analysis tools (clang-sanitize-undefined)	28s
Required checks complete	4s
	30m 20s

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