Issue token from OAuth server and pass it along with HTTP requests

Closes #2

See merge request gaia-x/data-infrastructure-federation-services/tsa/task!1

Migrate vereign to gaiax gitlab

See merge request gaiax/tsa-migrate/task!1

Replace LICENSE

See merge request !17

Expose prometheus metrics

Closes #19

See merge request !16

readme update

See merge request !15

Add max retry limit for task execution

Closes #18

See merge request !13

Add task execution documentation

Closes #17

See merge request !12

update

See merge request !14

init

See merge request !11

Task List Status Endpoint

Closes #15

See merge request !10

Parallel task list executor

Closes #14

See merge request !9

Sequential Task List executor

Closes #13

See merge request !8

HTTP endpoint to retreive task results

Closes #12

See merge request !7

* Create task unit tests
* Retrieve task results unit tests

Task execution of independent tasks

Closes #6 and #8

See merge request !4

We changed the design, so now tasks are either executing
a request policy, or an HTTP request to a predefined URL,
but not both.

In the previous commits "request policy" could only be used as
a request transformation and the actual task was executing an
HTTP request to a predefined URL. With the current change tasks
can execute "request policy" if it's set, or make an HTTP call.