RUMM-2204: Data is written in the SDK specific location

[0xnm]

What does this PR do?

This change brings support of dedicated storage folders for multiple SDK instances. Now each SdkCore instance will get a unique ID, which is sha256(token+site), and this ID will be used to create a root folder where this particular instance is going to store features data. Now, the folder structure will be like the following:

 datadog-b0f6d4ccffaa
   rum-pending-v2
   logs-v3
   traces-v4
 datadog-a4b6c1d4eebb
   rum-v5
   logs-pending-v6
   traces-v7

In the example above we have 2 instances of SdkCore running with IDs b0f6d4ccffaa and a4b6c1d4eebb.

CoreFeature now owns storageDir which will be the root for all the storage of the particular SDK instance. By referencing it from the persistence layer it is possible to remove Context references from many places.

SDK is still going to store files in the cache folder, in that sense nothing changed.

This change also cherry-picks f1890e1 to remove unused endpoints (in order to avoid adding unnecessary code) and removes file location migration (from files dir to cache dir), because anyway new file format for batches is not compatible with old SDK.

Similar to DataDog/dd-sdk-ios#906.

NB: If SHA-256 doesn't exist on the device there is no fallback, we don't proceed with SDK initialization. I think this is fine, because "this should never happen" (c) (unlikely that some OEMs is going to strip out such basic things from the OS build).

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[mariusc83]

I think these 2 first commits are from another PR ? Maybe you need a rebase ?

[0xnm]

The first commit is indeed from #973, I cherry-picked it explicitly, because it is on the develop branch.

[mariusc83]

LGTM