Path pattern matching is implemented via the doublestar package, which
emulates bash's globstar matching. Patterns may include '*' wildcard
characters (which match any number of non-separator characters), '**'
doublestars (which match zero or more subdirectories), '?' wildcard
characters (which match exactly one non-separator character), and nested
groups delimited by '{' and '}'. Notably, path patterns are *not* allowed
to have character classes delimited by '[' and ']', nor inverted
classes of the form "[^abc]".

There is a limit on the number of groups allowed in path patterns, but
up to that limit, groups may be arbitrarily nested or sequential.

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

i/prompting: fix typo and add notes to remove test boilerplate

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

i/prompting: use separate test suite for patterns

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

i/prompting: improve unit test coverage

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

Rather than counting the number of groups and using it as a heuristic
for the number of patterns into which a given path pattern will expand,
instead compute the true number of expanded patterns and compare it
against a set limit.

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

…erns

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>

Signed-off-by: Oliver Calder <oliver.calder@canonical.com>