[7.1.0] Introduce --default_test_resources flag (#21311)

Add `--default_test_resources=<resource>=<value(s)>` that allows setting
the default resource utilization for tests. The flag follow a syntax
simialar to `--local_resources=<resource>=<value>`, in that it allow
assigning different resource types, and `--test_timeout=<value(s)>`,
which accepts either 1 or 4 intergers to assign to all test sizes or to
each individually.

Relates to #19679

Closes #20839.

Commit
https://github.com/bazelbuild/bazel/commit/0c5b6e818a069bb61f2fc078eb8d1200002dc540



PiperOrigin-RevId: 606233269
Change-Id: Ia53e42820ba9aa646b0600fe4e9f95f146d7b2b9

Co-authored-by: Alessandro Patti <ale812@yahoo.it>