BUG: ResourceWarnings for unclosed files in boxlib frontend

[yut23]

Bug report

Bug summary

open() is used several times in the boxlib frontend without closing the files, triggering a ResourceWarning when the files go out of scope. Originally noticed by @neutrinoceros in https://github.com/yt-project/yt/issues/4845#issuecomment-2029735171.

Code for reproduction

Standalone reproducer using the ParticleCavity dataset:

import warnings
import yt

# enable all warnings
warnings.simplefilter("default")
ds = yt.load("plt.Cavity00010")

Actual outcome

/home/eric/build/yt/yt/frontends/boxlib/data_structures.py:701: ResourceWarning: unclosed file <_io.TextIOWrapper name='/scratch/yt-data/plt.Cavity00010/inputs' mode='r' encoding='UTF-8'>
  lines = [line.lower() for line in open(cparam_filepath).readlines()]
ResourceWarning: Enable tracemalloc to get the object allocation traceback
/home/eric/build/yt/yt/frontends/boxlib/data_structures.py:728: ResourceWarning: unclosed file <_io.TextIOWrapper name='/scratch/yt-data/plt.Cavity00010/Header' mode='r' encoding='UTF-8'>
  self._parse_header_file()
ResourceWarning: Enable tracemalloc to get the object allocation traceback
yt : [INFO     ] 2024-04-30 14:59:50,921 Parameters: current_time              = 0.017408426036316
yt : [INFO     ] 2024-04-30 14:59:50,921 Parameters: domain_dimensions         = [16 16  1]
yt : [INFO     ] 2024-04-30 14:59:50,921 Parameters: domain_left_edge          = [0. 0. 0.]
yt : [INFO     ] 2024-04-30 14:59:50,922 Parameters: domain_right_edge         = [1. 1. 1.]

Expected outcome

No warnings.

Version Information

• yt version: 4.4.dev0, cd4f1d69cd3f (current git head)