refactor: make create_cas_files generic

[github-actions[bot]]

Micro-Benchmark Results

Linux

group                          main                                   pr
-----                          ----                                   --
tarball/download_dependency    1.00      6.6±0.08ms   652.8 KB/sec    1.02      6.7±0.22ms   643.0 KB/sec

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (fa4638d) 86.43% compared to head (90bd628) 86.38%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #181 +/- ## ========================================== - Coverage 86.43% 86.38% -0.05% ========================================== Files 56 56 Lines 2838 2843 +5 ========================================== + Hits 2453 2456 +3 - Misses 385 387 +2 ``` | [Files](https://app.codecov.io/gh/pnpm/pacquet/pull/181?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pnpm) | Coverage Δ | | |---|---|---| | [crates/package-manager/src/create\_cas\_files.rs](https://app.codecov.io/gh/pnpm/pacquet/pull/181?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pnpm#diff-Y3JhdGVzL3BhY2thZ2UtbWFuYWdlci9zcmMvY3JlYXRlX2Nhc19maWxlcy5ycw==) | `91.66% <100.00%> (+2.19%)` | :arrow_up: | | [...ckage-manager/src/install\_package\_from\_registry.rs](https://app.codecov.io/gh/pnpm/pacquet/pull/181?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pnpm#diff-Y3JhdGVzL3BhY2thZ2UtbWFuYWdlci9zcmMvaW5zdGFsbF9wYWNrYWdlX2Zyb21fcmVnaXN0cnkucnM=) | `98.36% <100.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/pnpm/pacquet/pull/181/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pnpm)

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[github-actions[bot]]

Integrated-Benchmark Report (Linux)

Scenario: Frozen Lockfile

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
pacquet@HEAD	145.2 ± 10.4	128.4	163.2	1.06 ± 0.12
pacquet@main	137.0 ± 11.2	123.3	157.6	1.00

[KSXGitHub]

I changed my mind.