[Feature] Add option to not display sccache stats in workflow summary

[lcheylus]

With PR #113, there is now an annotation and a summary table with sccache stats for each job at the end of a workflow. sccache stats are also available in a "Post Run" step for each job.

For some jobs, I would like to have an option for this action to NOT add "sccache stats" in annotation and summary table. For example, add option stats (true by default):

uses: mozilla-actions/sccache-action@v0.0.5
with:
  version: "v0.7.4"
  stats: false

@orf As author of this PR, please could you add this option ?

Arguments for my request:

• I'm using the vmactions/freebsd-vm action to run some jobs/workflow on FreeBSD OS => FreeBSD VM run on an Ubuntu GH runner.
• In this FreeBSD VM, I'm using sccache action: install sccache FreeBSD package and set some env. vars for the action => sccache is correctly used in my job (build of a Rust project via cargo build).
• At the end of the FreeBSD job, "sccache stats" are always void because the command sccache --show-stats run on the Ubuntu runner, not on the FreeBSD VM where sccache is used.
• In conclusion, sccache stats displayed in annotation/summary table are useless in this case.
• I have a specific step/script in my FreeBSD workflow to get "sccache stats" in a text file and displays it.

[sylvestre]

@orf ping ? :)