[breaking] Remove url and checksum attributes from ToolPayload endpoint

[umbynos]

Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• Tests for the changes have been added (for bug fixes / features)

• What kind of change does this PR introduce?

change in the ToolPayload endpoint

• What is the current behavior?

url and checksum can be used to install tools:

$ curl -X POST --header 'Content-Type: application/json' --d
ata '{"name": "dummy","version": "dummy","packager": "dumm
y", "url": "https://dl.espressif.com/dl/esptool-2.3.1-linu
x.tar.gz","checksum": "SHA-256:cff30841dad80ed5d7d2d58a318
43b63afa57528979a9c839806568167691d8e"}' 127.0.0.1:8991/v2
/pkgs/tools/installed
{"status":"ok"}

• What is the new behavior?

We have removed the attributes, tools can be only installed using the package_index

$ curl -X POST --header 'Content-Type: application/json' --d
ata '{"name": "dummy","version": "dummy","packager": "dumm
y", "url": "https://dl.espressif.com/dl/esptool-2.3.1-linu
x.tar.gz","checksum": "SHA-256:cff30841dad80ed5d7d2d58a318
43b63afa57528979a9c839806568167691d8e"}' 127.0.0.1:8991/v2
/pkgs/tools/installed
{"name":"not_found","id":"73A55CXq","message":"tool not found with packager 'dummy', name 'dummy', version 'dummy'","temporary":false,"timeout":false,"fault":false}

• Does this PR introduce a breaking change?

yes

• Other information:

[umbynos]

Needs more work since the endpoint works a bit different to what I originally expected: If not index is added using 127.0.0.1:8991/v2/pkgs/indexes/add endpoint, the result of the usage of the endpoint is always "tool not found with packager 'arduino', name 'bossac', version '1.7.0'". The arduino package index should be added by default.

[umbynos]

Closing, since it's superseded by #826
Couple of notes:

• The arguments we wanted to remove are actually used by the Web Editor
• Removing completely url and checksum arguments causes any tool install to fail since the default index is not loaded by default, this requires a little refactoring (to load the default index without using the v2/pkgs/indexes/add endpoint).