Customize names of ignore files (support .gitignore etc)

[serhiy-storchaka]

Support of .neuroignore files was added in #1446.

We need to add support of other ignore files (e.g. .gitignore) and also an option to disable .neuroignore files.

The proposition is to add option --exclude-from-files to specify a space separated list of ignore files.

• --exclude-from-files=".neuroignore .gitignore" -- use both .neuroignore and .gitignore.
• --exclude-from-files=.gitignore -- use only .gitignore.
• --exclude-from-files= -- do not use any ignore files.

By default .neuroignore is used.

[serhiy-storchaka]

@asvetlov @YArtem

[atemate]

Good idea to avoid duplication of .neuroignore and .gitignore! If we add the flag neuro cp --exclude-from-files, will the corresponding .neuro.toml entry be automatically supported? Similar to what we have to exclude:

[storage]
cp-exclude = ["*.log"]