Implement analyze mode for embed-code-go.

[vb-td]

In this PR, the analyze mode was added.

Now, it is possible to run program to find the code embeddings which don't have corresponding code fragments for them. All corresponding information is written to the build/analytics/embeddings-not-found-files.txt file.
Here is example of the typical record in this file:

error for file C:/Users/user/project/_i18n/en/docs/8/guides/authentication.md, missing embeddings: 
java/guides/authentication/Examples.java — Proxy check
kotlin/kt/guides/authentication/Examples.kt — Proxy check
java/guides/authentication/Examples.java — Basic auth
kotlin/kt/guides/authentication/Examples.kt — Basic auth
java/guides/authentication/Examples.java — Cancel auth
kotlin/kt/guides/authentication/Examples.kt — Cancel auth
java/guides/authentication/Examples.java — Select client certificate
kotlin/kt/guides/authentication/Examples.kt — Select client certificate
java/guides/authentication/Examples.java — Cancel certificate auth
kotlin/kt/guides/authentication/Examples.kt — Cancel certificate auth
java/guides/authentication/Examples.java — Select custom certificate
kotlin/kt/guides/authentication/Examples.kt — Select custom certificate

Also, the information about changed embeddings collected as well. All corresponding information is written to the build/analytics/embeddings-changed-files.txt file.
Here is example of some typical records in this file:

en\docs\8\guides\authentication.md : EmbeddingInstruction[file=`kotlin/kt/guides/authentication/Examples.kt`, fragment=`Select custom certificate`, start=`<nil>`, end=`<nil>`]
en\docs\8\guides\browser.md : EmbeddingInstruction[file=`java/guides/browser/Examples.java`, fragment=`Create browser from profile`, start=`<nil>`, end=`<nil>`]
pt\docs\tutorials\integration\selenium.md : EmbeddingInstruction[file=`/tutorials/selenium/launcher/src/main/java/SeleniumLauncher.java`, fragment=``, start=`Pattern *import*`, end=`<nil>`]

Additionally, the error-handling flow has been modified. Previously, if any error occurred during the processing, the entire flow would stop. This behavior made it impossible to scan all embeddings and collect comprehensive analytics. Now, if any error occurs, the flow continues, the encountered errors are collected as artifacts, and no embeddings are performed as a result.

[armiol]

LGTM with the respect of some comments to address first.

[dmytro-kashcheiev]

@vb-td LGTM with some minor comments

[dmytro-kashcheiev]

Can we have continue here or maybe else if since it take time to understand why we need to check changedEmbeddings even in case of errors.

[vb-td]

It is confusing, but it can be many embeddings in one file, some of them can cause an error and some of them can be changed. So it is made by intention. I can comment this part or just don't check the file for changed embeddings if any error occurs.