Dynamic OpenSSL library integration enhancements

[yashwantsahu20]

Following are the required enhancements,

1. Current way of finding out installed openssl library has some issue, like if ssl.h is installed in some other apps folder in system directory. It may set to use same path for OpenSSL and this is flawed.
   We need add better way to find out installed path. One way to use pkg-config --cflags openssl

2. Add provision to add custom OpenSSL folder path in makefiles.

Steps to use custom openssl library:
Note: Tested with openssl 3.5.1 version

1. Download openssl source code.
2. ./config --prefix=/home/ysahu/project/custom_ssl/openssl_custom_ins
3. make
4. make install
5. Compile ProxySQL using

make CUSTOM_OPENSSL_PATH=/home/ysahu/project/custom_ssl/openssl_custom_ins