Merge changes from topics...

Merge changes from topics "revert-2746976-revert-2605644-rulebuilder-ninja-vars-OAAWYCDDLT-KMAGKVIXAT", "sandbox-rust-inputs" into main

* changes:
  support sandboxed rust rules
  conditionally escape rule builder command
  Revert^2 "allow Ninja variables in RuleBuilder API"
  Revert^2 "add crate_root property to rust modules"
  Revert^2 "add rust_toolchain_rustc_prebuilt module type"