Allow --purs-args to be passed to 'purs bundle'

[felixSchl]

For spago bundle-app and spago bundle-module it is currently impossible to pass arguments straight down to purs. We're running into extremely long build times on Circle CI due to PureScript detects more cores than are actually available. We get around that by setting --purs-args='+RTS -N2 -RTS'. However, this only works for spago build, not for the bundle commands (

spago/src/Spago/Build.hs

Line 280 in 083ef16

bundleAction = Purs.bundle withMain (withSourceMap buildOpts) moduleName targetPath

). To highlight the severity of the issue, for our project bundeling without those flags takes somewhere between 17 and 20 minutes, whereas with the flag set it only takes about 45 seconds. We are temporarily falling back to just invoking purs directly for bundling.

[f-f]

I just realized this is a duplicate of #216, I'll close this one as that has more info