Remove GetReadOnly from deploysource.Provider interface

[khanhtc1202]

What this PR does / why we need it:

This PR removes GetReadOnly from deloysource.Provider interface in pipedv1 package. The implementation of GetReadOnly does not provide any protections but only means that "please ensure not to modify the deploy source" or things will go wrong.

Concerning point: The GetReadOnly does not copy the deploy source directory, while the Get interface does, which means using the Get interface is more costly than using the GetReadOnly. But, for the new implementation of pipedv1, we will introduce another mechanism for controlling the deploy source, which is: instead of lazied cloning the deployment source (as the current usage of the deploy source package), we will force the piped clone the deployment source before call to plugins interfaces.

Also, this change is in the pipedv1 package, which means it would not affect our current users 👍

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 22.46%. Comparing base (2841574) to head (3c90a4b).

Files	Patch %	Lines
pkg/app/pipedv1/executor/cloudrun/deploy.go	0.00%	2 Missing ⚠️
pkg/app/pipedv1/controller/scheduler.go	0.00%	1 Missing ⚠️
pkg/app/pipedv1/executor/cloudrun/rollback.go	0.00%	1 Missing ⚠️
pkg/app/pipedv1/executor/ecs/deploy.go	0.00%	1 Missing ⚠️
pkg/app/pipedv1/executor/ecs/rollback.go	0.00%	1 Missing ⚠️
pkg/app/pipedv1/executor/lambda/deploy.go	0.00%	1 Missing ⚠️
pkg/app/pipedv1/executor/lambda/rollback.go	0.00%	1 Missing ⚠️
...pedv1/plugin/platform/kubernetes/planner/server.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5048      +/-   ##
==========================================
- Coverage   22.46%   22.46%   -0.01%     
==========================================
  Files         522      522              
  Lines       57041    57026      -15     
==========================================
- Hits        12816    12810       -6     
+ Misses      43198    43189       -9     
  Partials     1027     1027              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.