Update plugin-tooling.mk, Update tanzu builder init to include plugin-tooling.mk to build and publish plugins

[anujc25]

What this PR does / why we need it

• Update plugin-tooling.mk within the repo.
• Add a make plugin-install-local target to install locally built plugins.
• Update builder plugin templates to use the new plugin-tooling.mk file to build the plugins.

Which issue(s) this PR fixes

Fixes #86

Describe testing done for PR

# Initialize a new repository
$ tanzu builder init hello-world --repo-type github
$ cd hello-world

# Add a new plugin with name foo
$ tanzu builder cli add-plugin foo

# Commit the base changes
$ git add -A
$ git commit -m "Initialize plugin repository"

# Go get the latest tanzu-plugin-runtime from the main branch. [NOTE: This step should not be needed once we have an official tag on the `tanzu-plugin-runtime` repository]
$ go get github.com/vmware-tanzu/tanzu-plugin-runtime@main
$ make gomod

# Building Plugin
$ make plugin-build-local

# Installing plugins from a local source
$ make plugin-install-local

# OR Combined Build and Install target is also available
$ make plugin-build-install-local

# Publish the plugin as oci image to the local oci repository
$ make plugin-publish-packages

# Combined target to build and publish plugins
$ make plugin-build-and-publish-packages

# Initialize a local inventory database by running the below command
$ make inventory-plugin-add

# Add plugin to the local inventory database
$ make inventory-plugin-add

# Configure below environment variable to point to the inventory database as discovery image 
$ tanzu config set env.TANZU_CLI_ADDITIONAL_PLUGIN_DISCOVERY_IMAGES_TEST_ONLY localhost:5001/test/v1/tanzu-cli/plugins/plugin-inventory:latest

# Run plugin search
$ tz plugin search
  NAME                DESCRIPTION                                                        TARGET           LATEST
  foo                 foo plugin v2                                                      global           v0.0.0

Release note

Update `tanzu builder init` to include `plugin-tooling.mk` file containing the tooling to build and publish plugins

Additional information

Special notes for your reviewer

[marckhouzam]

Two minor nits only.

[vuil]

lgtm