Add strict schema

[tom-tan]

This request introduces a strict schema for cwltest as a preparation of #110.
Here is a difference of cwltest-schema and strict schema.

• id field is limited to string,
• label field is removed, and
• tags field is mandatory

It enable us to migrate to a new schema and enable us not to introduce a regression that uses current schema with integer id field.
Note that it is not to enforce a new schema because it breaks existing systems that depend on the current schema of cwltest.

It is also important to add deprecation and migration messages in cwltest but it is out of scope of this request.

[codecov]

Codecov Report

Merging #138 (398e2d9) into main (b65f9b7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #138   +/-   ##
=======================================
  Coverage   60.04%   60.04%           
=======================================
  Files           2        2           
  Lines         453      453           
  Branches      133      133           
=======================================
  Hits          272      272           
  Misses        139      139           
  Partials       42       42           

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[tom-tan]

ping!

[mr-c]

Thanks!