Rename repository/plugin

[uniqueg]

Related to #3 ("native" TES executor): As it is probably a good idea to keep this executor implementation around, at least until a better one is available, it may be a good idea to rename this repository and plugin, then implement #3 in a separate repository.

Possible names I could think of are snakemake-executor-plugin-tes-smk (to highlight that it wraps TES tasks in Snakemake calls) or snakemake-executor-plugin-tes-legacy (to highlight that this represents the old/first way of using the TES backend in Snakemake).

The new implementation could perhaps be named snakemake-executor-plugin-tes (the name of this repo/plugin; to highlight that we at least plan that to be the preferred version) or snakemake-executor-plugin-tes-native (to highlight that more responsibility will be put on TES implementations in the way envisioned by TES creators and maintainers).

@vsmalladi @MattMcL4475 @svedziok @vschnei @kellrott