`Genie.newapp_*` functions create lots of read-only files

[tecosaur]

Describe the bug

Calling any of the newapp_* functions that make cp calls like https://github.com/GenieFramework/Genie.jl/blob/173d8e3deb47f20b3f8b4e5b12da6bf4c59f3370/src/Generator.jl#L347 also copy the read-only file permissions, which is a bit of a pain when this is done for files you want to be immediately editable.

Expected behaviour

Read-write files would be nice.

Additional comments

Could replacing cp calls with walkdir + cp + chmod or walkdir + write help? The files created by write calls seem to be fine, and that has a decent chance of respecting the system's umask.