add bndtools workspace template fragment

[chrisrueger]

This adds a Workspace Template Fragment which can be used by bndtools users to create a new Bnd Workspace.

See https://bnd.bndtools.org/chapters/620-template-fragments.html for more information.

Next steps

After this folder is available on github (e.g. in master branch):

• we add an entry in https://github.com/bndtools/workspace-templates/blob/master/index.bnd pointing to this folder in the tycho repo

Onces that is done, all bnd tools users will see a new entry for Eclipse Tycho Maven in bndtools, like this:

Why

It is just a useful addition to promote the ability of Tycho to build Bnd Workspaces.

[chrisrueger]

All suggestions fixed. I moved more stuff to BndBuild.md

[laeubi]

It overall looks good to me, please squash your commits into one so we can easier back-port this!

[github-actions]

Test Results

  606 files  ±0    606 suites  ±0   4h 20m 11s ⏱️ + 21m 4s
  434 tests ±0    426 ✅ ±0   7 💤 ±0  1 ❌ ±0 
1 302 runs  ±0  1 279 ✅ ±0  22 💤 ±0  1 ❌ ±0 

For more details on these failures, see this check.

Results for commit 6f500ad. ± Comparison against base commit 807bd8e.

[merks]

I think the suggest changes will improve the documentation (of this cool new feature).

[chrisrueger]

Thanks a lot @merks for the readme suggestions. I committed them all.
@laeubi I squashed all commits. Ready to go I think.

[laeubi]

Build will not verify this ..

[eclipse-tycho-bot]

💚 All backports created successfully

Status	Branch	Result
✅	tycho-4.0.x

Note: Successful backport PRs will be merged automatically after passing CI.

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details