Cannot build the nodejs client following the Readme

Start with the README instructions for npm run build and compare them with the existing macOS script that builds libpulsarwithdeps.a. Check how the Linux build should produce that library, then document the required steps; done means the README workflow completes successfully on Ubuntu without the missing-library error.

System: Ubuntu-18.04

When I followed the readme to build the client, it threw following errors at the npm run build step:

make: Entering directory '/workspaces/pulsar-client-node/build'
  SOLINK_MODULE(target) Release/obj.target/Pulsar.node
g++: error: ../pkg/lib/libpulsarwithdeps.a: No such file or directory
make: *** [Pulsar.target.mk:157: Release/obj.target/Pulsar.node] Error 1
make: Leaving directory '/workspaces/pulsar-client-node/build'
gyp ERR! build error 
gyp ERR! stack Error: `make` failed with exit code: 2
gyp ERR! stack     at ChildProcess.onExit (/opt/nodejs/17.6.0/lib/node_modules/npm/node_modules/node-gyp/lib/build.js:194:23)
gyp ERR! stack     at ChildProcess.emit (node:events:527:28)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (node:internal/child_process:291:12)
gyp ERR! System Linux 5.4.0-1090-azure
gyp ERR! command "/opt/nodejs/17.6.0/bin/node" "/opt/nodejs/17.6.0/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "build" "--module=/workspaces/pulsar-client-node/lib/binding/Pulsar.node" "--module_name=Pulsar" "--module_path=/workspaces/pulsar-client-node/lib/binding" "--napi_version=8" "--node_abi_napi=napi" "--napi_build_version=0" "--node_napi_label=node-v102"
gyp ERR! cwd /workspaces/pulsar-client-node
gyp ERR! node -v v17.6.0
gyp ERR! node-gyp -v v8.4.1
gyp ERR! not ok 
node-pre-gyp ERR! build error 
node-pre-gyp ERR! stack Error: Failed to execute '/opt/nodejs/17.6.0/bin/node /opt/nodejs/17.6.0/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js build --module=/workspaces/pulsar-client-node/lib/binding/Pulsar.node --module_name=Pulsar --module_path=/workspaces/pulsar-client-node/lib/binding --napi_version=8 --node_abi_napi=napi --napi_build_version=0 --node_napi_label=node-v102' (1)
node-pre-gyp ERR! stack     at ChildProcess.<anonymous> (/workspaces/pulsar-client-node/node_modules/@mapbox/node-pre-gyp/lib/util/compile.js:89:23)
node-pre-gyp ERR! stack     at ChildProcess.emit (node:events:527:28)
node-pre-gyp ERR! stack     at maybeClose (node:internal/child_process:1090:16)
node-pre-gyp ERR! stack     at Process.ChildProcess._handle.onexit (node:internal/child_process:302:5)
node-pre-gyp ERR! System Linux 5.4.0-1090-azure
node-pre-gyp ERR! command "/opt/nodejs/17.6.0/bin/node" "/workspaces/pulsar-client-node/node_modules/.bin/node-pre-gyp" "build"
node-pre-gyp ERR! cwd /workspaces/pulsar-client-node
node-pre-gyp ERR! node -v v17.6.0
node-pre-gyp ERR! node-pre-gyp -v v1.0.9
node-pre-gyp ERR! not ok 

Cannot find the libpulsarwithdeps.a. I found that there is a script to build the libpulsarwithdeps.a on the macos system but not for the linux system. I think we may need to update the Readme.

/cc @shibd