feat: add C implementation for @stdlib/stats/base/dists/erlang/logpdf

[rautelaKamal]

This PR adds a C implementation for @stdlib/stats/base/dists/erlang/logpdf.

Closes #3571

Changes

• Added src/addon.c: Node.js native addon entry point

• • Added src/main.c: C implementation delegating to stdlib_base_dists_gamma_logpdf
• • Added include/stdlib/stats/base/dists/erlang/logpdf.h: C header file
• • Added lib/native.js: JavaScript wrapper for native addon
• • Added benchmark/benchmark.native.js: Native benchmark
• • Added manifest.json: Build manifest
• • Updated package.json: Added gypfile, include, and src directories

• Read, understood, and followed the contributing guidelines

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/erlang/logpdf	$\color{green}198/198$ $\color{green}+100.00%$	$\color{green}9/9$ $\color{green}+100.00%$	$\color{green}2/2$ $\color{green}+100.00%$	$\color{green}198/198$ $\color{green}+100.00%$

The above coverage report was generated for the changes in this PR.