Sync script for updating frontend

[alexanderzobnin]

This PR adds some helpful scripts for syncing changes with upstream changes in open source Grafana. It's a bit tricky since we have slightly different code (imports, some dependencies), but looks promising. Script gets a latest changes in the elasticsearch data source folder and then formats it as a git patch. Changes only fetched from the last sync (last sync commit hash is stored in the .upstream.lock file). In most of cases git patch fails, but I use 3 way merge, so changes can be reviewed and applied manually. Example of usage:

alex@alex-ws:es-open-distro-datasource$ ./sync-changes.sh 
Switched to and reset branch 'sync-upstream'
Creating new branch
Switched to a new branch 'sync-upstream-f1b3c8ba4b9f2a3f3f35d8dd092de541784eac67'
Syncing changes with base commit
Getting list of files to sync (ref f1b3c8ba4b9f2a3f3f35d8dd092de541784eac67)
Downloading files
[sync-upstream-f1b3c8ba4b9f2a3f3f35d8dd092de541784eac67 0592813] Sync changes with commit f1b3c8ba4b9f2a3f3f35d8dd092de541784eac67
 25 files changed, 186 insertions(+), 119 deletions(-)
 create mode 100644 src/README.md
 create mode 100644 src/img/elasticsearch.svg
 rewrite src/plugin.json (65%)
Syncing changes with master
Master branch is on f4fcd875c16c67eff36b0535d556417c54e53399
Getting list of files to sync (ref master)
Downloading files
Writing master commit into lockfile
Creating a patch
Cleaning up and applying patch
Switched to branch 'sync-upstream'
error: patch failed: .upstream.lock:1
Falling back to three-way merge...
Applied patch to '.upstream.lock' cleanly.
error: patch failed: src/datasource.ts:9
Falling back to three-way merge...
Applied patch to 'src/datasource.ts' cleanly.
Deleted branch sync-upstream-f1b3c8ba4b9f2a3f3f35d8dd092de541784eac67 (was 0592813).
Patch applied. Now you can review changes and apply it manually if patch failed.

[Elfo404]

Took this for a spin and seems to work like a charm.

I think is an awesome starting point, left a couple of comments just to think about a couple of points, but IMO it's good to go.

[Elfo404]

shouldn't this be a dev dependency?

[alexanderzobnin]

Not sure. This required for running script. I'll check it out.

[Elfo404]

maybe we can start with bb45f5fedc (which is the react migration commit) as we did a few changes both here and in upstream. What do you think?

[Elfo404]

I was thinking that instead of this we might want a config file with local/path <-> upstram/path for each file/dir we need to sync, so that this would also take care of dependencies for example. wdyt?

[alexanderzobnin]

Yes, sounds good. Maybe we can reorganize files a bit to make it easier to sync.