feat: support tgz for bundled plugins

[YOU54F]

closes #48

This feels like the code could be dry'd a bit, maybe doing a seperate file extension lookup, then checking the naming convention, then offloading to the correct downloader, but possibly fine for now.

can be tested by

git@github.com:pact-foundation/pact-plugins.git
git checkout feat/targz_plugin_binaries
cd cli
cargo run install https://github.com/austek/pact-avro-plugin/releases/tag/v0.0.4

This will fail, is run from master or from the released binary

pact-plugin-cli install https://github.com/austek/pact-avro-plugin/releases/tag/v0.0.4

[github-actions[bot]]

Unit Test Results

6 tests  ±0   6 :heavy_check_mark: ±0   7s :stopwatch: +2s 2 suites ±0   0 :zzz: ±0  2 files   ±0   0 :x: ±0 

Results for commit dd3359c1. ± Comparison against base commit f57ddf3e.

:recycle: This comment has been updated with latest results.

[rholshausen]

The JVM driver will need to be updated to support this as well.