feat: add subscriptionMaxEvents for maximum number of notifications (geofencing)

[maxl2287]

What type of PR is this?

Add one of the following kinds:

• enhancement/feature
• correction

What this PR does / why we need it:

• Based on the updated guidelines the subscriptionMaxEvents is added as an optional parameter to define after how many events the subscription will end. (Geofencing API - Adding capability to manage max number of notification #111)
• Define the subscriptionExpireTime as optional in the descriptions (subscriptionExpireTime is declared as "required" in the subscription-ends - note, but is optional currently #161)

Which issue(s) this PR fixes:

Fixes #111
Fixes #161

[bigludo7]

Thanks for the quick update @maxl2287
For the update look good for me but looking for @jlurien view on the version. Shifting to V0.2 for this API makes sense but we want to close Release V0.2 (for all 3 APIs) so perhaps we have to wait to merge this one. See @jlurien comment here: #160

[maxl2287]

@bigludo7 v0.2.0 for DeviceLocation was released yesterday.
This is the new version for Geofencing API, which will be v0.2.0 for this API next, but will be included in the next DeviceLocation release v0.3.0.

That's why I used here v0.2.0-wip.

[jlurien]

Yes, until we have clear rules for API family versioning, I think we should continue with our current one, so new updates on geofencing should be part of 0.2.0-wip

[jlurien]

I suggest to consolidate #162 on this to avoid with conflicts

[maxl2287]

thanks for the review.
I will adapt the changes and close the other one

[jlurien]

LGTM

[bigludo7]

LGTM