feat(ptt): Add space ptt feature to features (#299)

For PTT, in order to ensure that the default lockfile-less logic (to
only generate graphs in the absence of a lockfile) is overridden when a
customer is using PTT, we need a way to communicate the status of the
PTT feature to the CLI from the app. As such, this PR introduces
`path_to_transitivity` as an optional (for backwards compatibility)
boolean value on `feature` .

An alternative I was exploring was adding a field to the `scan_config`
and `scan_response` objects which could store a list of "feature flags"
and their values/enabled status from the app in order to avoid having to
make changes to interfaces in the case that we want feature flag
behavior to affect the way `semgrep-pro` works. However, with this
approach, the main con is that we would need to ensure that the names of
the feature flags stay consistent between the CLI and the app which
would open us up to bad bugs resulting from silly things like typos.

With the approach in this PR (just tacking PTT onto the list of features
in the config), the main con is that principally the `features` entry
gets its values from settings stored as part of the config in
`postgres`. In addition, once PTT is GA, this feature flag becomes
useless so ideally, we will update lockfileless to generate the graph by
default and then remove code which checks the PTT flag and then
altogether from interfaces.

- [x] I ran `make setup && make` to update the generated code after
editing a `.atd` file (TODO: have a CI check)
- [x] I made sure we're still backward compatible with old versions of
the CLI.
For example, the Semgrep backend need to still be able to *consume* data
generated
	  by Semgrep 1.17.0.
See
https://atd.readthedocs.io/en/latest/atdgen-tutorial.html#smooth-protocol-upgrades

Author: SayyantR

semgrep_output_v1.atd

@@ -1218,6 +1218,7 @@ type features = {
    ~autofix: bool;
    ~deepsemgrep: bool;
    ~dependency_query: bool;
+   ~path_to_transitivity: bool;
 }
 
 type triage_ignored = {