Implement new commands `build` and `check` + introduce bundles (.contract files) (#97)

* Fix URIs

* Make `generate-metadata` output consistent with `build`

* Add `cargo contract pack`

* Return error instead of panicking

* Use blake2_hash()

* Replace match with if

* Pass reference instead of ownership

* Generate metadata.json and <contract>.pack

* Output .wasm, .json, .pack

* Return result object instead of tuple

* Get it to run with '--features test-ci-only'

* Rename .pack to .contract

* Apply suggestions from code review

Co-authored-by: Alexander Theißen <[email protected]>

* Introduce '--skip-packing' and '--skip-metadata'

* Apply suggestions from code review

Co-authored-by: Alexander Theißen <[email protected]>

* Short help message

* Output deprecated error for 'generate-metadata'

* Rename pack ➜ bundle

* Add 'cargo contract check' command

* Optimize resulting Wasm file, except on 'check'

* Do not make unoptimized file easily mistake for optimized one

* Get it to run with

* Update readme

* Make unoptimized wasm not show up in target folder

* Update comments

* Remove 'generate-metadata' variants

* Move dispatch logic into metadata

* Update src/main.rs

Co-authored-by: Alexander Theißen <[email protected]>

* Move logic into build.rs

* Improve progress output

* Make clippy happy

* Fix progress output

* Make it work with `--features test-ci-only`

* Apply cargo fmt

* Always use optimized Wasm for metadata hash

* Always use optimized Wasm for metadata hash

* Make it work with `--features test-ci-only`

* Switch naming

* Fix metadata/bundle output

* Use enum `BuildArtifacts` instead of boolean flags

* Improve misleading fn name

* Make it work with `--features test-ci-only`

* Make output more concise

* Print optimization result at the end

* Improve output

* Replace 5-tuple return value with struct

* Include hash only for bundle in metadata

* Make it work with `--features test-ci-only`

* Fix doc test

* Remove comments

* Introduce wrapper type CodeHash

* Make it work with `--features test-ci-only`

* Display important results bold

* Include size diff for `code-only` as well

* Remove comment

* Shorten code

* Clone metadata for correct UI output

* Remove unnecessary return

* Fix return type

* Print metadata generation in correct step

Co-authored-by: Alexander Theißen <[email protected]>