make loadPackages() work for big build.zig files

[teh-cmc]

Hey there, I'm currently working on a project in which the build.zig file has been steadily growing, and at some point my ZLS just stopped working: no autocompletion, no gotodef, no nothing for any package outside of std. :(

Turns out the culprit was the loadPackages function that execs some parsing stuff and pipes back the output... unfortunately the default parameters for exec only allow up to 50k of data to be collected through stdout by default ¯\_(ツ)_/¯.

[SuperAuguste]

Hey, thanks for your contribution! This change does indeed work, but it demonstrates an underlying issue with the build runner. I would prefer a refactor that implements a streaming solution that does not require 52 megabytes of allocated stdout buffer to function!

[theoparis]

Hey, thanks for your contribution! This change does indeed work, but it demonstrates an underlying issue with the build runner. I would prefer a refactor that implements a streaming solution that does not require 52 megabytes of allocated stdout buffer to function!

I was just attempting to implement this. Would a "streaming solution" be considered using a while loop and a [4096]u8 buffer with readUntilDelimiterOrEof? I also split the ChildProcess.exec() to seperate spawn, read, wait calls.