Update memory-testing Dockerfile to use cargo-chef (#259)

## 🎟️ Tracking

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point to where this change is coming from. -->

## 📔 Objective

The previous Dockerfile was trying to copy only the Cargo.toml and
creating fake lib.rs files in an attempt to build the dependencies
before the rest of the source code was copied, which would help with
build caching and improve build times considerably. This was very error
prone and would break any time extra workspace dependencies were added.

This PR migrates that process to use `cargo-chef` instead, which
automatically handles that process for us. The dependencies get cached
just as well as before, but we don't need to fiddle with creating fake
lib.rs to make the compiler happy.

I've also updated the dockerignore to include some files that were
previously missing.

## ⏰ Reminders before review

- Contributor guidelines followed
- All formatters and local linters executed and passed
- Written new unit and / or integration tests where applicable
- Protected functional changes with optionality (feature flags)
- Used internationalization (i18n) for all UI strings
- CI builds passed
- Communicated to DevOps any deployment requirements
- Updated any necessary documentation (Confluence, contributing docs) or
informed the documentation
  team

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that's not quite a confirmed
  issue and could potentially benefit from discussion
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Author: dani-garcia

crates/memory-testing/Dockerfile

@@ -1,38 +1,28 @@
 ###############################################
 #                 Build stage                 #
 ###############################################
-FROM rust:1.85 AS build
-
+FROM rust:1.85 AS base
 WORKDIR /app
 
-# Copy dependency files and create dummy files to allow cargo to build the dependencies in a separate stage
-COPY Cargo.toml Cargo.lock /app/
-COPY crates/bitwarden-crypto/Cargo.toml /app/crates/bitwarden-crypto/
-COPY crates/memory-testing/Cargo.toml   /app/crates/memory-testing/
-
-# Patch Cargo.toml to remove `, "bitwarden_license/*"` from the members array
-RUN sed -i 's/\([" ]*\)"bitwarden_license\/\*"[ ,]*\([" ]*\)/\1\2/g' Cargo.toml
-
-RUN mkdir -p /app/crates/bitwarden-crypto/src \
-    /app/crates/bitwarden-crypto/benches \
-    /app/crates/memory-testing/src \
-    && touch /app/crates/bitwarden-crypto/src/lib.rs \
-    /app/crates/bitwarden-crypto/benches/default_allocator.rs \
-    /app/crates/bitwarden-crypto/benches/zeroizing_allocator.rs \
-    && echo 'fn main(){}' > /app/crates/memory-testing/src/main.rs \
-    && cargo build -p memory-testing --release
-
-# Delete dummy files and copy the actual source code
-RUN rm /app/crates/bitwarden-crypto/src/lib.rs \
-    /app/crates/bitwarden-crypto/benches/default_allocator.rs \
-    /app/crates/bitwarden-crypto/benches/zeroizing_allocator.rs \
-    /app/crates/memory-testing/src/main.rs
-
-COPY crates/bitwarden-crypto /app/crates/bitwarden-crypto
-COPY crates/memory-testing/src   /app/crates/memory-testing/src
-
-# Build the project. We use touch to force a rebuild of the now real files
-RUN touch /app/crates/bitwarden-crypto/src/lib.rs /app/crates/memory-testing/src/main.rs
+# Make sure the correct rust toolchain is installed only once
+COPY rust-toolchain.toml /app/
+RUN rustup show
+
+# Install cargo-chef, to cache dependency builds
+RUN cargo install cargo-chef --version 0.1.71 --locked
+
+# Prepare the recipe for the dependencies, which will be built as the first part of the next stage
+FROM base AS planner
+COPY . /app/
+RUN cargo chef prepare --recipe-path recipe.json
+
+# Build dependencies based on the recipe of the previous stage, then copy the source and build the project
+FROM base AS build
+COPY --from=planner /app/recipe.json recipe.json
+RUN cargo chef cook -p memory-testing --release --recipe-path recipe.json
+
+# Copy the source here to reuse the cached dependencies
+COPY . /app/
 RUN cargo build -p memory-testing --release
 
 ###############################################

crates/memory-testing/Dockerfile.dockerignore

@@ -1,4 +1,6 @@
 *
-!crates/*
-!Cargo.toml
-!Cargo.lock
+!/crates/*
+!/bitwarden_license/*
+!/Cargo.toml
+!/Cargo.lock
+!/rust-toolchain.toml