Changes in 7.5.0

WIP

Allow explicit index filenames for P2 repositories

Behavioral impact by setup

Existing setup	Before branch	After branch
No location configured	Creates cnf/cache/p2-<name>/index.xml.gz	Same, because new default ends in /
Explicit path ending in / or \	Directory mode	Same
Explicit path without separator, directory already exists	Directory mode	Same
Explicit path without separator, directory does not exist yet	Directory mode	Explicit index-file mode; behavior changes
Explicit path pointing to an existing file	Fails because it was treated as a directory	Works as explicit index file
Explicit custom index filename in a new parent directory	Not supported	Supported; bundles go beside the index

# reference a p2 repository with a given index file name
eclipse.p2.repository.4.40: \
    aQute.bnd.repository.p2.provider.P2Repository; \
        name     = 'Eclipse P2 Platform 4.40'; \
        url      = 'https://download.eclipse.org/eclipse/updates/4.40'; \
        location = '${.}/eclipse_4.40_platform_p2.index.xml.gz'

# re-use (and checkin) the created index from above to avoid future parsing time
eclipse.osgi.repository.4.40: \
    aQute.bnd.repository.osgi.OSGiRepository; \
        name      = 'Eclipse Platform 4.40'; \
        locations = '${fileuri;${.}/eclipse_4.40_platform_p2.index.xml.gz/index.xml.gz}'