feat: Add support for setting/adding entire tables/arrays

[simifalaye]

#38 Added support for reading and editing toml array values but there was no way to add an array into the toml document since it would always be interpreted as a table. This PR aims to add support for setting/adding entire tables (including nested tables) and arrays by looking at the keys of the lua table in the __newindex meta-method to determine which one it is. Note that just like the last PR, only arrays of basic value types are supported (no arrays of tables).

[simifalaye]

@vhyrro @mrcjkb

[mrcjkb]

@simifalaye I updated toml-edit to version 0.6.0 in nvim-neorocks/rocks.nvim#574.
The tests are failing, for example with

bad argument #2: error converting Lua string to i64 (expected number or string coercible to number)
stack traceback:
        [C]: in function '__newindex'
        spec/operations/pin_commands_spec.lua:104: in function <spec/operations/pin_commands_spec.lua:101>

It appears that one of the changes in this PR was breaking.
Pinning toml-edit to 0.5.0 in rocks.nvim, until this has been fixed.

[mrcjkb]

Posting this for linking purposes: #42