Content of local plugins referenced by relative path, are not excluded for lambda bundles

[medikoo]

Use case description

Local plugins listed via relative paths (as ./path/to/plugins - feature introduced with #6261) are not subject to auto exclusion from lambda bundle, as it's the case with plugins put to ./.serverless_plugins folder.

They should be excluded as well.

Proposed solution

1. When loading plugins build list of all local plugin paths (and store at e.g. pluginManager.localPluginsPaths - it should also include local path)
2. When generating exclude list, automatically add all those paths to the list