path update for helm charts

[acelinkio]

relates to #747 updates the helm chart to specify paths and avoid the need for rewrite rules.

[acelinkio]

@zoriya , i can change the target for this MR to your feature branch if you'd like. note that this will pull in some changes from master branch.

I don't exactly follow why the /video path needs to be specified in the transcoder url. Eventually I'll get around to building/publishing the containers to test more locally.

[zoriya]

Some routes of the transcoder return URIs that should be reachable from the front (that was the previous use case of the GOCODER_PREFIX env var.) The c# back proxies this api under /video so we need to specify this prefix value (and it changes the listen route to include this prefix.)
On v5, the transcoder will be accessed directly without the proxy so it will be less weird x)

PS: you can keep targeted to master, i'll merge the PR branch soon. I just wanna test a bit more & see if it would break https://github.com/arthi-chaud/meelo to merge it like that.