[EPIC] Extension manifest

[kavilla]

TODO: Update references when we source control the example extension.

Problem:

Plugins have a plugin manifest defined as opensearch_dashboards.json [EXAMPLE].

The role of the manifest file is to describe the set of required and optional properties of a plugin such as plugin name version and other required plugins. [SOURCE]. It also the resource that is checked with verifying which version of OpenSearch Dashboards the plugin is compatibility with. This is very dependent on plugin developers This is not conducive towards to having a robust semantic versioning system based on dependencies and runtime checks since this file is read before run time.

Solution:

Within the de-couple RFC, there is talks about dependency checks.

We can build in version checks, dependencies like other plugins, extensions, APIs, backend dependencies, OpenSearch Dashboards versions.

Requirements:

• [Research] SDK dependencies API #36
• [Implement] SDK dependencies API #37