.editorconfig: unify free-standing bash indent with Nix-embedded bash indent (#388089)

[*.{json,lock,md,nix,rb}]

indent_size = 2

# Match perl/python/shell scripts, set indent width of four

[*.{bash,pl,pm,py,sh}]

# Match all the Bash code in Nix files, set indent width of two

[*.{bash,sh}]

indent_size = 2

# Match Perl and Python scripts, set indent width of four

[*.{pl,pm,py}]

indent_size = 4

# Match gemfiles, set indent to spaces with width of two