Move lead and cycle time classes out from Group NS

What does this MR do?

This MR makes the cycle time and lead time figures available on the project-level. Note: the FE part is not available yet, so the change is not user-facing. This is an EE change because the cycle time and lead time needs license.

Code move: Move files from Gitlab::Analytics::CycleAnalytics::Summary::Group to Gitlab::Analytics::CycleAnalytics::Summary to have generic classes which work for both the group and project level features.

How to test it:

1. Make sure you have a premium license.
2. Seed VSA: SEED_VSA=true FILTER=cycle_analytics rake db:seed_fu
3. Visit the generated project path (check the output)
4. Copy the project path and replace the URL: http://localhost:3000/GROUP_PATH/PROJECT_PATH/-/analytics/value_stream_analytics/time_summary.json?created_after=2019-05-01
5. The endpoint should load. It's likely that you won't see any data. (-)

Screenshots (strongly suggested)

Group-level view. Note: project-level view is not available yet:

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #327570 (closed)