feat(flake): use sccache in the dev shell

[dpc]

This should improve compilation times when switching between branches etc.

You can view the sccache with sccache --show-stats:

> sccache --show-stats
Compile requests                   2093
Compile requests executed          1501
Cache hits                         1150
Cache hits (Rust)                  1150
Cache misses                        339
Cache misses (Rust)                 339
Cache timeouts                        0
Cache read errors                     0
Forced recaches                       0
Cache write errors                    0
Compilation failures                 11
Cache errors                          0
Non-cacheable compilations            0
Non-cacheable calls                 592
Non-compilation calls                 0
Unsupported compiler calls            0
Average cache write               0.008 s
Average compiler                  0.564 s
Average cache read hit            0.004 s
Failed distributed compilations       0

Non-cacheable reasons:
crate-type                          456
incremental                         125
-                                    11

Cache location                  Local disk: "/home/dpc/.cache/sccache"
Use direct/preprocessor mode?   yes
Version (client)                0.7.4
Cache size                          937 MiB
Max cache size                       10 GiB

[justinmoon]

dev call: implications for disk usage?

[dpc]

dev call: implications for disk usage?

Cache size                          937 MiB
Max cache size                       10 GiB

It auto-GCs and is capped at 10GiB (can be changed locally by the user).