cptbox: let compilers specify required dirs

Some compilers require directories to write to, specifically, ZIG and 
SWIFT require `.cache`

dmoj/executors/RUST.py

@@ -84,6 +84,7 @@ class Executor(CompiledExecutor):
     compiler_write_fs = [
         RecursiveDir('~/.cargo'),
     ]
+    compiler_required_dirs = ['~/.cargo']
 
     def create_files(self, problem_id, source_code, *args, **kwargs):
         os.mkdir(self._file('src'))

dmoj/executors/SWIFT.py

@@ -9,6 +9,7 @@ class Executor(CompiledExecutor):
         RecursiveDir('~/.cache'),
     ]
     compiler_write_fs = compiler_read_fs
+    compiler_required_dirs = ['~/.cache']
     test_program = 'print(readLine()!)'
 
     def get_compile_args(self):

dmoj/executors/ZIG.py

@@ -10,6 +10,7 @@ class Executor(CompiledExecutor):
         RecursiveDir('~/.cache'),
     ]
     compiler_write_fs = compiler_read_fs
+    compiler_required_dirs = ['~/.cache']
     test_program = """
 const std = @import("std");
 

dmoj/executors/compiled_executor.py

@@ -81,6 +81,9 @@ class CompiledExecutor(BaseExecutor, metaclass=_CompiledExecutorMeta):
     compiler_read_fs: Sequence[FilesystemAccessRule] = []
     compiler_write_fs: Sequence[FilesystemAccessRule] = []
 
+    # List of directories required by the compiler to be present, typically for writing to
+    compiler_required_dirs: List[str] = []
+
     def __init__(self, problem_id: str, source_code: bytes, *args, **kwargs) -> None:
         super().__init__(problem_id, source_code, **kwargs)
         self.warning = None
@@ -95,6 +98,14 @@ def create_files(self, problem_id: str, source_code: bytes, *args, **kwargs) ->
         with open(self._code, 'wb') as fo:
             fo.write(utf8bytes(source_code))
 
+        for path in self.compiler_required_dirs:
+            path = os.path.expanduser(path)
+            assert path == os.path.abspath(path), 'paths in compiler_required_dirs must be absolute after expanding ~'
+            try:
+                os.mkdir(path, mode=0o775)
+            except FileExistsError:
+                pass
+
     def get_compile_args(self) -> List[str]:
         raise NotImplementedError()