Fix linux arm compiling and add CI for cross-compiled builds

[devm33]

This PR fixes the cross-compilation for linux arm builds to correctly use the sysroot and adds CI for cross-compiling.

The added CI caught an issue that the cross-compiled build was not correctly using the sysroot and linking against the wrong GLIBC version. Installing the correct cross-compilation toolchain fixes that.

Also fixes a duplicate trailing slash here:

node-pty/src/utils.ts

Line 20 in 772905e

const dir = `${r}/${d}/`;

Used here:

node-pty/src/unixTerminal.ts

Line 17 in 772905e

let helperPath = native.dir + '/spawn-helper';

• Follow up to Add sysroot to compile Linux prebuilds against glibc 2.28 #853
• cc Add prebuilt linux binaries with minimal glibc dependency #851