feat(tools): Templates can be imported from node_modules/

[vladitasev]

This feature allows .hbs template authors to:

• Import other .hbs files from anywhere in the local filesystem: path starting with . or ..
• Import other .hbs files from node_modules/

Examples:
{{>include "./Popup.hbs"}}
{{>include "../my_partials/Header.hbs"}}
{{>include "@ui5/webcomponents/src/ListItem.hbs"}}

This will enable third party developers to extend our components and implement the partials.

For the purpose, we need to start shipping the src/ directory of main and fiori.

In addition, some parts of the hbs2lit and hbs2ui5 libs have been improved, most notably includesReplacer in order to be able to recursively parse include statements while simultaneously keeping track of the current relative path of the currently parsed file so that relative references inside it can work properly.

closes: #1859