Pass filesystem to file operations.

[delucchi-cmu]

Change Description

Second attempt at #311

Related to issue #307.

[github-actions]

Before [0459650]	After [8374aee]	Ratio	Benchmark (Parameter)
87.5±3ms	90.4±1ms	1.03	benchmarks.Suite.time_paths_creation
984±20μs	999±20μs	1.02	benchmarks.time_test_cone_filter_multiple_order
19.2±0.7ms	19.4±0.6ms	1.01	benchmarks.MetadataSuite.time_load_partition_info_order6
13.0±0.2ms	13.1±0.2ms	1.01	benchmarks.Suite.time_inner_pixel_alignment
40.9±0.9ms	41.1±0.8ms	1	benchmarks.Suite.time_pixel_tree_creation
76.7±1ms	76.2±1ms	0.99	benchmarks.MetadataSuite.time_load_partition_info_order7
77.0±1ms	75.3±0.4ms	0.98	benchmarks.MetadataSuite.time_load_partition_join_info
383±5ms	374±3ms	0.98	benchmarks.Suite.time_outer_pixel_alignment
118±0.8ms	116±0.8ms	0.98	benchmarks.time_test_alignment_even_sky

Click here to view all benchmarks.