feat(core): do not update template if dockerfile is modified

[m-alisafaee]

Description

A Renku-specific section can be added to a Dockerfile. Any lines of the Dockerfile that are between begin and end end markers must not be modified by users. This section is used to calculate Dockerfile checksum (empty lines and whitespaces at the end of lines are ignored). If it's missing then we use the whole Dockerfile.

When updating a template, Renku only update this section if it exists in both project and template Dockerfile; otherwise, the whole Dockerfile is overridden.

########################################################
#        Renku-specific section - DO NOT MODIFY        #
########################################################


########################################################
#              End Renku-specific section              #
########################################################

Fixes #3354

[coveralls]

Pull Request Test Coverage Report for Build 4813552425

• 69 of 74 (93.24%) changed or added relevant lines in 7 files are covered.
• 6 unchanged lines in 6 files lost coverage.
• Overall coverage increased (+0.03%) to 85.331%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
renku/core/template/template.py	9	10	90.0%
renku/core/migration/migrate.py	10	12	83.33%
renku/domain_model/template.py	37	39	94.87%

Files with Coverage Reduction	New Missed Lines	%
renku/command/migrate.py	1	94.51%
renku/core/template/template.py	1	86.44%
renku/core/template/usecase.py	1	89.71%
renku/core/workflow/activity.py	1	93.61%
renku/ui/cli/init.py	1	96.9%
renku/ui/cli/service.py	1	68.59%

Totals
Change from base Build 4810277066:	0.03%
Covered Lines:	25543
Relevant Lines:	29934

---

💛 - Coveralls

[olevski]

A few suggestions and questions.

Do we need more extensive documentation changes to explain the formating and content of the Dockerfile sections and logic?

[olevski]

Thanks Mohammad.